Its more unweildy than that! Each state (AFAIK) has its own State Board of Education that decides curriculum, textbooks and administers examinations. There is additionally a Central Board with its own syllabus and exams, and for good measure, a few other additional Boards (ICSE, etc).
Then there are the mediums of education within the State Boards. In Tamil Nadu, for example, subjects are taught in two mediums: English and Tamil. Its been a while since I looked at the Tamil medium textbooks, but I do believe they are translated into the language from English, where relevant.
That said, the curricula [??] do tend to broadly track each other and lead only to moderate pain at the college level. There is probably some collaboration among the various boards -- I have an aunt who served a senior Education officer... her email use is sparse, but I will ping her nonetheless, for more info.
-- Horace Lowell