-Ryo and Ryu. Ryo almost 100% reminds me of Ryu and shoto characters in SF. He has one of the strongest ground games in KOF 13 with high priority, fast ground normals, and a fireball shield that is difficult to get past. He has a fireball, a traditional Street Fighter DP, and a move very similar to a SF shoto's tatsu. He also has a parry, so 3rd Strike fans may take a liking to him, although you can't quite use his parry the same way you would parry in 3S.
-Yuri and Akuma. Yuri has Akuma's demon flip, and an air fireball. You can do demon flip mixups with Yuri similar to how you would with Akuma in 3s (canceling demon flips from ground normals), except Yuri's demon flip has stupid good crossup potential compared to Akumas, and her demon flip throw is less effective outside of combos.
If I remember correctly, the original Art of Fighting had several former Capcom employees who worked on it, so it is not surprising the Sakazaki clan and Robert are obvious clones of the Shotos.
Dan and Sakura from the Street Fighter II universe are deliberate parodies by Capcom of Ryo, Robert, and Yuri.
Dan's "fireball" is a parody of when Ryo, Robert, or Yuri's spirit meter in Art of Fighting II is empty and no fireball comes out. Dan even has his own Hien-shippu-kyaku, just like Ryo. Also, in Street Fighter Alpha, one of Dan's win quotes is, "I want to win the King of Fighters and not Street Fighter." I kid you not. Go play it if you don't believe me.
This has been common knowledge in the Fighting Game community for over 15 years.
Art of Fighting and Fatal Fury took a lot from Street Fighter and Street Fighter II since those games were SF and SF2's contemporaries.
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As for differences between SF and KOF games in general, the most obvious is:
Boss fights:
Akuma, Dictator, Gill, Urien, and Seth are far, far easier to defeat than any SNK boss, but that's pretty obvious.