I have played Chris quite a bit at SDCC, and even in just gameplay videos it's obvious they are so different it's not even funny.
"She uses guns just like Chris!"
- B.B. Hood's gun is just her HP, it literally is just a multi-hitting melee move. Chris is a special move that changes depending on the button pressed: A Magnum that causes a wallbounce, a shotgun with spread shot, and flamethrower which is pretty much useless. There is no similarity at all. Literally. The only thing that could work is during her super with the hunters, and even then that should need no explanation.
"They both have a flamethrower!"
- As I mentioned before, Chris's flamethrower is ********, with B.B. Hood it's a great move. With three inputs now they can make it aim straight forward, then a 45 degree angle, then a 75 degree angle, adding one more angle to what was in MvC 2. Or they could make it like Vampire Saviour 2 where she spreads it back and forth, but I would prefer to keep it like MvC 2. Also she can do it in the air. Besides EVERYONE uses fire in this game :/
"Ok... explain the land mines then!"
-Again a special with different properties which can create fire on the floor on waits for someone to step on it (actually useful fire unlike his flamethrower) vs a kick that has more range.
What about B.B. Hoods missiles? What about her basket swing? Her command roll/crawl? Her unique supers? Command normals? Having a completely different moveset and input? Do none of these matter?
Besides they love Dante/Deadpool. Both are smart aleck, red and black wearing, sword users and gunslingers. They even share a super move.
"THIS IS DIFFERENT!!!! DEADPOOL IS SO COOL!!"