All these are India's premiere training institutes , the point of difference lies between there mode of entry , type of commision and age limit

IMA DEHRADUN

Mode of entry : Direct and TGC

Age limit : 19 to 24 and 20 to 27 years resp

Type of commision :permanent



OTA CHENNAI

Mode of entry :ssc tech and ssc non tech

Age limit :19 to 25 years

Type of commision :short service , can be extended



OTA GAYA

Mode of entry : 10+2 (Pcm) based on marks

Age limit 17 to 19.5

Type of commision: permanent.

Hope it helped.