Rachel requires a constant poke-based game up close and she's lather lacking at mid to long range, since most of those tools are linear. Leon has a better time getting in with 46P and he actually has a low crush from mid range with 9P and 6P+K and 33OH to keep people honest.
Leon's basic strikes are 11/13/16 while Rachel's are 11/13/14. She does have that few frame lead in terms of advantage and her low tracking move is 18i while Leon's is 22i, though Leon benefits from the extra frame of safety on normal hit and trip stun on CH. Rachel's more poke-based, really. She's very basic. Both have 2Ps that are +1, so they can end up with similar 10/12 high/mid strikes. Pretty good.
In the mix-up department, Rachel kind of loses here, because despite being safe, she can occasionally lose to mid-punch holds. Leon just has a better low-mid mixup. Both characters have very good tracking strings like PK for Rachle and P6P for Leon, but he's the one that has the added follow ups. It makes it easier to open people up and it also benefits from safe mid and low followups.
In terms of tracking, Leon doesn't have fast enough mid tracking moves which means that the Leon player has to make more use of P6P and 6PP, which is a bad thing necessarily, but his standalone tracking more are much slower than Rachel's. Rachel has a good 18i 1P and 16i 4PP string. Yes, a low of people buffer mid punch hold when buffering their own strings, but 4P on its own is pretty good, which makes her a simple decent MU to pick against Brad who has a slightly better time against other heavies until their start using their low OH.
In terms of working towards max threshold or just getting to that CB, Leon has an easier time than Rachel, because 3P, 7P, 8K, 33P these are all good and you can god around that depending on how much you charge P+K. He also has a good SDS with 3K on crouching opponents which he also has in this 6PK string. Stagger escaping him can be difficult. Rachel on the other hand has a good lift stun with 3P and two good SDS on hit, though due to her recovery, it's a little easier to escape hers. 8K 7P is a pretty good idea most of the time, but if you get caught, you leave yourself open to be punished. Not like Leon is super safe; he's got unsafe moves too, but people don't punish him as much for some reason.
In terms of oki, I actually won't rate Rachel higher than Leon mainly because Leon has a better blender than Rachel. Sure, she was pretty good when she came out, but now she is downright punishable. Leon has low throws and they benefit from whiffing into low throws instead of ground throws, which means that usually you have better recovery and so you end up actually being at frame advantage. Now, the king of this whole ground throw blender is Bass, but Leon can also play this game, especially after wall crumble and he does pretty good damage if he catches you not teching. I've found that Leon ends up in more of those situations in general than Rachel. Commitment with Leon is less risky than with Rachel. The risk-reward scale with both characters seem fair, but Leon has to risk less than Rachel.
Both characters basically fall into the same category as the poke-based heavy weight characters whom you can adopt their own rushdown style. Yes, they can rush you down in certain situations. They're both good, but there's no question that Leon's total damage output is superior to Rachel's outside of her 41236T, which comes close to Leon's.
Okay, you guys did talk about movement in general and Rachel's hurtbox in neutral is smaller and some stuff can whiff on her from range 3-4, like Kasumi's 6K 1K. Honestly, I wouldn't rate that too high in this MU, but it does count still. For these characters, they have to be right in your face, though Leon can do things from range 2, as in like two characters away.
So, overall who does better against Kasumi? It think they can both hold their own against her, but overall, you'd probably expect Leon to do a bit better based on his overall tools and he has a pretty good high crush with 33P.
I can't give these MUs numbers tbh. I just feel like they can both do well and this isn't like the Kasumi-Bass MU where you have to struggle a lot to get ball rolling.