I found this on a web actualy so yeah~ ^^

1. They were both trained for at least seven years under SME.

2. Their favorite song in the Girls’ Generation album is Complete.

3. They are both blood type B.

4. They both have very big and beautiful eyes.

5. They are both natural beauties.

6. They were two of the most popular trainees back in their pre-debut days.

7. They are two of the most popular members in SNSD.

8. They both received an unexpected hug from fans during SNSD’s first trip to Vietnam.

9. They both love to pout.

10. Despite their quiet personalities, they both love to whisper and gossip.

11. They both love to reply to UFOs and they had mentioned each other in their replies for numerous times.

12. They both share an infamous habit of -ing.

13. During the same Genie performance, they both tried to end the life of a bug by stepping on it.

14. They both had the octopus hairstyle at one point.

15. They are both the ideal girls of 2PM.

16. They both have very light skin.

17. They are both close with the ex-trainee, Stella.       

18. They both have y foreheads.

19. They were both featured in SUJU MVs.

20. Their pairings with Yuri are both very popular.

21. They both tend to clap their hands a lot when laughing.

22. They are both close with SUJU Heechul.

23. They both had exchanged messages with SUJU DongHae on cyworld during their pre-debut days.

24. They both love to eat chickens.

25. Their pairings with SUJU DongHae are both very popular.

26. They were both mentioned in KyuHyun’s thanks-to and are both close with him.

27. They both have mole(s) on their left cheek.

28. They both had camera fear.

29. They both can play instruments.

30. They both like to prank their members.

31. They both do not like aegyo, but are oozing with it.

32. They both had kissing scenes during their acting activities.

33. They both wore a star necklace.

33. They have couple rings.

34. They are easily cracked up even when they are on stage performing.

35. They had both appeared on Strong Heart as the main guests.

36. During their appearance on Strong Heart, they were confessed to by their admirers.

37. They both did Heechul’s Sorry Sorry ending pose.

38. They both like gentle men.

39. They love to stick their tongue out a lot.

40. They have very similar sleeping poses.

41. They both (sarcastically) think they are born to cook.

42. This is why they complete each other: Yoona’s popularity among fanboys is evidenced by her endless list of admirers and Jessica’s popularity among fangirls is evidenced by the fact that she always tops polls that are voted by lesbians.

43. They are the only SNSD members whose names both ended with letter A.

44. Their personal collectibles had the highest bidding prices in one of the auctions.

45. They both wore a star sticker under their eye during Genie performances.

46. They both wear glasses and contact lenses.

47. They both admitted that they are not ambitious people.

48. They both had appeared on musical performances.

49. They both had no bangs during their pre-debut days. 

50. They both wore bangs during the RDR days.

51. They both had the highest rate of negative feedback when their solo shots for RDR were released.

52. They both lost to their opponent during the Champagne’s SS501 Special.

53. They both have animal-related nicknames: Jessica’s ‘dolphin scream’ and Yoona’s ‘alligator mouth’.

54. They both have food-related phobias: Yoona fears chicken feet and Jessica fears cucumbers.

55. They both have special features of their bodies: Jessica’s ‘Golden Hips’ and Yoona’s ‘Yumabs’.

56. They both wrote “if we make any mistakes, please just ignore them” in their airplane letters.

57. They were the only ones who went for cutesy concept for their solo stages during the SNSD’s 1st Asia Tour Concert.

58. They had both received lessons from the members of CSJH: Dana coached Yoona in singing, while Stephanie gave Jessica dancing lessons.

59. During their tour concerts, they were both performing with two male guests: Jessica with two members from Shinee; Yoona with two members from SUJU.

60. They are the only two members who explicitly confessed that they want to get married soon.

61. They both want to get married at the age of 27 or 28.

62. They both had a lot of pre-debut pictures, individually and together.

63. They were in the same team in one of SNSD hunting games at Lotte; four years later, they were in the same team yet again in another SNSD hunting games at Phuket.

64. They both got 12% of votes for the “Who is the prettiest SNSD member?” poll one of the French forums.

65. They both tried to cake each other during their birthday—though Jessica’s attempt failed.

66. Before they went to Japan, they both wrote a message to fans telling them not to cheat on SNSD.

67. 2PM Junho’s mom  likes YoonSic a lot and thinks that they make good wives.

68.  Their magazines (along with Taeyeon’s) were both sold out a day right after Seohyun’s.

69. They took their Driver’s Test at the Donga on Wednesday and successfully passed it on the same day.

70. Yoona was Sooyoung’s ex-roommate, while Jessica is Sooyoung’s current roommate.

71. In their All About Girls’ Generation self talk, they both made playful attempts in interrupting one another’s speech.

72. While the other members complain about Yoona’s peculiar aegyo, Jessica loves it (please note that Jessica usually despises aegyo).

73. When Jessica was asked to pick among the younger girls, she picked Yoona as the cutest.

74. When Yoona was asked to pick who is the prettiest during the Gee era, she picked Jessica.

75.  Yoona loves Jessica’s duet song with Onew: One Year Later.

76. If you did pay attention to the beginning pose of Gee where JeNy stand in front of Yoona, you would realize nine out of ten times, Yoona would always look at Jessica instead.

77. During ITNW performances, Jessica is in the center at the beginning and Yoona is in the center at the ending pose.

78. They both have a sister: Yoona has an older sister while Jessica has a younger sister.

79. During the break between their performances, YoonSic would usually share and drink from the same water bottle.

80. Jessica’s solo picture was printed on Gee album while Yoona’s solo picture was printed on Tell Me Your Wish album.

81. If you did not know, Yoona has a for Jessica’s hair as she keeps touching it whenever she has a chance.

82. Yoona said that Jessica is a very caring person and she cheers for her a lot: “Jessica unnie said ‘you should try hard before give up and just believe yourself’ to me.”

83. Jessica is one of SNSD’s lead singers, while Yoona’s one of SNSD’s lead dancers.

84. Jessica is the second oldest member while Yoona is the second youngest member.

85. Physically, Yoona is the strongest member of the group while Jessica is the weakest.

86. Their hairstyles were totally opposite from the Gee to Genie era. Jessica wore her hair short during the Gee era while Yoona wore her long and the opposite is true during the Genie era.

87. During a dance collaboration between SNSD and Shinee, Yoona was paired up with Taemin (Shinee’s main dancer) while Jessica was paired up with Jonghyun (Shinee’s main singer).

88. Yoona’s waistline is 22 inches—Jessica’s number in OH! is 22.

89. Yoona said in Vogue Magazine that her ideal type is a person who is calm and gentle and sweet, and who can lead her well. Does that statement not scream Jessica Jung, the warm ice to you?

90. Arguably, Jessica’s voice is the most feminine among the SNSD members whereas Yoona’s is the manliest—they really complement each other.

91. In regards to their laughing habit, they both like to cover their features while laughing: Jessica covers and Yoona covers her eyes.

92. In All About Girls’ Generation, Jessica declared that Yoona is her endorphin.

93. Yoona shares an uncanny resemblance with Jessica’s little sister, Krystal. Are they not destined to be a family?

94. In one of the making of RDR, Jessica randomly asked Yoona if she is her manito (which is the person Yoona has to show affection to in a certain game) and it turned out that she, in fact, is.

95. During SNSD hunting game in Phuket, Jessica did not seem energetic when she was teamed with Sooyoung and Seohyun. But as soon as Yoona switched team with Sooyoung and became her teammate, Jessica started to play more seriously and their team immediately started to win.

96. They were both advised by SM to keep their image: SM told Yoona to act more feminine; SM also told Jessica to quit playing soccer so that she would not ruin her face.

97. Touchiness aside, they both are not very good at expressing their thoughts.

98. Jessica’s Japanese name is Shika, which means deer in Japanese; deer is often associated with Yoona.

99. They both tend to hide their tears. Yoona has the habit of standing alone by herself to cry every time SNSD won awards; Jessica has the habit of leaving the scene to cry by herself whenever SNSD has arguments.

100. It is believed that SNSD donated a considerable amount of money to the Japan disaster under fake names—Im Yoona was known as Yoona Jung.

Keke~ That's all xD