Hi Bryony,
I am not a yogi, but a beginner in the practice.
Gaiam Life says that there are 8 major yoga styles:
1. Anusara
2. Ashtanga
3. Bikram
4. Hatha
5. Hot Yoga
6. Iyengar
7. Restorative
8. Vinyasa
I have practiced Hatha Yoga, Kundalini Yoga and a spot of Hot Yoga but that's it so far.
Let us know if you have found out any other information on yoga and share.
Thanks,
Selina