I'm not an expert on them. IOSPE lists differences and you can compare if you have both pages open at the same time. The main difference that jumped out at me are:
- bellina broad, rounded, light green leaves, larger than violacea; 2" flowers; citrus scent; summer/fall blooming.
- violacea elliptical, obtuse, undulate, gradually narrowing below leaves, smaller than bellina; 1.4" flowers; cinnamon/spice scent; spring blooming.
I'll throw in some speculation here.
- Line breeding may lead to flowers and leaves of different size than wild species. It certainly leads to different color patterns.
- Phal. violacea was described in 1861. Phal. bellina was described as a variety of Phal. violacea in 1884. They come from different islands. Bellina was not separated from violacea until 1995. They were both in cultivation before 1995 as Phal. violacea. It seems to me very likely the two species have been crossed in the past by people who thought they were the same species. Without knowing the detailed history of your plant's breeding, all the way back to known-locality wild-collected plants, it might be hard to say whether it is a pure species or contains ancestry from both of these species. This would apply to all bellinas and violaceas without detailed ancestry information.