Only sparkling wines made in the region of Champagne, France are allowed to be called Champagne. Sparkling wine made elsewhere (India included) have to call themselves sparkling wine.

So to answer your question, the difference between Indian sparkling wine and Champagne is where the sparkling wine was made.

Sparkling Italian wine is called Prosecco.

No, despite the urban legend, sparkling wine and still wine will affect you equally.

For Sparkling wine it is sealed in its container to allow the natural gases to make the wine sparkling. Still wine allows the gases to escape and a wine that still has gases is credited with not being ready to drink yet.

Champagne is a sparkling wine