Hyderabadi and Lucknowi biryani are built on basmati - long, separate grains that stand apart from the masala. Kolkata biryani leans long-grain too.
The short-grain south
Thalassery biryani in Kerala is made with jeerakasala rice. Ambur and Dindigul biryani in Tamil Nadu use seeraga samba. Small aromatic grains that absorb the masala instead of standing apart from it.
The same family, from Bengal.
Gobindobhog is a GI-protected short-grain aromatic from West Bengal - the same grain family as jeerakasala and seeraga samba. Aged well, it cooks fluffy and separate, suited to biryani and ghee rice.
Different biryanis, different grains !
Eastern India Rice Mill (EIRM) - Gobindobhog aged up to 2 years, milled at source in Purba Bardhaman. Wholesale across Kerala, Tamil Nadu & Karnataka.