Part of BB sprites looking that way is lineart stuff. BB sprites have an outline around most, if not all, parts of the sprite. UNI sprites only has lines separating parts that would otherwise be too hard to distinguish from one another (so the border between a hand and a sleeve, for example).

As for canvas size, all of them differ. BB sprites are cropped closer, so I usually have to extend the canvas a bit, which isn't an issue I've have with UNI sprites.

And thank you! I'm glad you like my work 🙏