Are you traveling to or from India? Because almost all airlines offer a vegetarian meal going to and from India, the food will be different in each class and its almost always prepared in an Indian style.

I think you only have to order a Hindu meal if you have connecting flight segments that are not coming to or from India.

Lets say you were flying from JFK to DEL on BA and you requested a Hindu meal. On the JFK to LHR segment you will get a special hindu vegetarian meal prepared in a south asian style. The menu for the LHR to DEL segment will always have a vegetarian option cooked in a south asian style so they might not have to load a special meal for you since the regular menu already has the option. Oh yeah another difference is they might serve you first but the tray might be one of the options offered to the rest of the cabin you just get it first to make sure they dont run out since you were specific about your dietary requirements.

Its simmilar for EK. All meals on all EK flights are Halal so you only have to request a Halal meal if your booking has a connection with one of EKs partner airlines. If you request a Halal meal for an EK flight you will be offered the regular menu. So if you fly from YYZ to CDG on AC your meal will be special but from CDG to DXB on EK you will just get the regular menu since everything is Halal. EK will always have a standard meal option that is Hindu Veg aswell as Halal on flights to and from India.

Its the same concept with LY. If you request a Kosher meal you will be offered the regular menu since all meals are Kosher even the special meals are Kosher. I dont know what they offer on segments to and from India though.

Ive flow several airlines from YYZ to DEL with a connection and all the segments to and from DEL offer an indo vegetarian meal. But im not vegetarian so I just eat the regular menu on non Indian segments.