How does Biryani differ from Pulao.

Pullao preparation is based on the principle of  absorption method of cooking rice. Whereas Biryan is made by draining method. Pulao originated in Persia. In both Biryani and Pulao meat can be used. For vegetarians, vegetables are used.

I think it's only the language that sets them apart. Punjabis esp Muslims in our part of the country and in south call it Biryani. Maybe the vegetarian and non-vegetarian makes the difference too. 

Kalyani has already given the exact difference between the two, however nowadays many restaurants do not follow the age old method of layering while making Biriyani, tend to mix everything..I prefer the layering method and then cooking it for a while after sealing the sides . The flavors remain trapped inside and it adds to the taste.

Preperation defference

For me Biryani is non vegetarian, Chicken biryani, Mutton Biryani and pulao is vegetarian. Add vegetables in rice, it is pulao.

Biriyani and Pulao differ in their method of cooking and in the masala/spice contents. I think biriyani is more spicy. But ultimately both of them tinkle our taste buds.

When I make pulav, I add vegetables like carrot and beans into the rice and I cook chicken or mutton as a side dish for pulav. For vegetarians, we can prepare tasty vegetable dishes like gobi manchurian or chilli paneer. But when I make biriyani, I add meat and rice together for non-vegetarians and rice and variety of vegetables for vegetarians.