I actually just had both up side by side (4 on 360, 5 on ps3) and went down Nicole's movelist, seeing how much of it actually carried over to Rachel.
I skipped the moves that are exactly the same (plus maybe a couple of the first strings because I didn't start up ps3 till after that.)
8PP (rachel only has 8p, not the following straight punch)
3ppp (rachel's version is a much slower string of swinging mids)
3pp6ppp (Rachel doesn't have any options like this)
3ppkk (rachel can't switch to kicks off 3pp like nicole could)
6PPP (Rachel doesn't have the 3rd punch, only 6PPK version)
6pkk (Nicole's original felt faster)
4PP (Nicole could delay/charge the second P, unlike Rachel, although Rachel can continue the string for 4PPPP, while Nicole's simply shot the opponent backwards after the second P)
46P (Leon's tackle, Rachel is lacking it)
236p (Rising upper)
214p (Overhead slap, while Rachels 214 is essentially Nicoles old 236p)
3(Hold)P a straight hook, while all Rachel can do from that is her standard jab.
33p ( a quick diagonal crushing punch. Rachel has no options there)
66p (Nicoles was a high, not a mid, but thats mostly due to Nicole being way taller, also Nicoles sent them flying)
4k (Nicole had a spinning round house, Rachels is a standard small punt)
6kp (Nicoles P was the downshot from her 33p, while Rachels seems to be a slightly slower double armed full overhead, seemingly to make up for the difference in height)
8k (Nicoles was a launching up kick, Rachels is an overhead drop kick)
66p (Nicoles was faster)
4P+K (Nicole was a stance that led to a straight punch (but could be confused for kick version), while Rachels is the same double overhead from 6kp preceded by a small hop. So again, Nicoles was faster)
H+K (NIcoles was a quick rising knee to the face, Rachels is a slow roundhouse)
4H+K (Same stance as 4P+K, but leads to a kick instead, good for mixup from the stance. Rachel just has another slow spinning high kick)
3H+K (Nicole had a quick ankle sweep, Rachel tries to do her stomp even if the opponent isnt grounded. They should give her the quick sweep if the opponent isn't grounded, leaving the stomp as a down attack)
T (Quick face punch like Mila now has for Nicole, but slower than Mila's, a judo throw to the ground for Rachel)
4T (Holding the opponent up, then punching them back for Nicole. For Rachel, just a judo throw backwards, leaving them both grounded and getting up)
6T (for Nicole, Bayman's little "stomp on their foot and knee them to the side", for Rachel, its Nicole's 4T, but instead of knocking them away, she punches them up and lets them fall down, again, seemingly only good for setting up the stomp)
41236T (Nicole: Plasma throw, Essentially just holding them up, punching them, then kicking them back. Rachels version is the same except bouncing them off the ground instead of the kickback at the end)
214T (Lift up, punch, ground bounce, for Nicole. This became Rachels hcirlceT, only Nicole's bounced way higher with more hangtime.)
T to opponents back (Quick neck punch, like standard T throw, only to the back of the opponents head, leaving them stunned, Rachel has a leaping head drop that leaves both characters getting up. Nicoles seems far more useful)
4T, 4T on backfacing opponent (Leon/Bayman's hanging neck tree, only good for its own damage, but rachel has no other options against standing backfacing opponents, so another tool would be nice)
3T against crouching opponent (Nicole crushes and does a high groundbounce to the opponent, Rachel just does a quick little hit with her butt that barely even stuns. I think Rachel should get that ground bounce.)
2T against crouching opponents (Nicole does a necklift and punches them back, sending them flying, Rachel does an armlock and drops them with no ground bounce)
High Punch Hold (Nicole catches the punch, does two full armbars, the second slamming the opponent to the ground by their face. Rachels does a spinning trip punch that pushes the opponent away)
Mid Punch Hold (Nicole, does Leon's "Turnaround, neck snap, kick away", Rachel, punches the opponents feet out from under them and then does an overhead, driving them to the ground)
Mid Kick Hold (Nicole: Catches the kick and punches the opponent straight into the air, good for Followups. Rachel, same thing but a spinning double handed punch)
Low Punch Hold (NIcole, quickly catches punch and hits opponent to the ground face down next to her. Rachel: Long leaping throwdown that leaves opponent grounded)
Jumping Punch Hold (Nicole catches the opponent and face slams them to the ground. Rachel....i dunno what of Ayanes moves are aerial punches so I have a hard time checking)
Jumping Kick Hold (Nicole, catches and punches them face up to the ground by their stomach)
I discovered later that a couple of Nicoles moves were moved to different inputs on rachel, but ONLY a couple, not even enough to bother listing.
So overall, while Nicole couldn't do the extended combos Rachel can, she had WAY more options, with the moveset being geared more towards giving space, solid strikes, and bouncing the opponent off the environment (like Leon), while Rachel's actual strings and strikes suck for anything other than setting up her air throw or stomp, with most of her moves being slow and wonky, and half of her grabs and holds being no good for followups, leaving her kinda helpless if she can't set up her combo. I don't MAIN Rachel, but that's what I got off of just comparing the movelists in training. I really think they should merge more of Nicoles old set with Rachel to give her some better options.
It's this the reason because I don't agree with who want her being totally different in the aspect (but being fair, neither this is completely true because if you put the faces in comparison you can actually say who is the original and who is the clone for subtle but evident differences). However this wasn't important from what I was saying, like I said I was answering to your post where you were talking about movesets, not physical features.
