You need to examine and compare the spicules, gambles or megascleres for definitive identification. But the best way is to submit photos and samples to a museum or expert on macrobenthia (but you could argue they are microbenthic too!) :-)
Sure Identification cannot be done from a photograph alone (unless perhaps if you know your local freshwater sponge fauna very well). As said by Andrew you need to examine the skeleton and gemmules into detail. I am not sure how well Indian freshwater sponges are investigated, and if your sponges are from local waters, it is an interesting part of the subcontinent, where you also could meet species not yet scientifically described. Your freshwater sponges probably all belong to the demosponge suborder Spongillina and you can make a not too difficult start by using the fine chapter on this group by R. Manconi & R. Pronzato in "Systema Porifera. A Guide to the Classification of Sponges". Kluwer Academic/Plenum Publishers 2002.. Volume 1: 921-1019. Andrew's suggestion that you ask some specialist to do it, it pure lottery; nowadays taxonomic specialists are comparatively few and most are already busy. But you can try.
I can't help with I.D. at all. But these are neat sponges. How big are they? I encounter some in New Zealand rivers, but they are more like a small mat. I wonder where the colour comes from - the sponge or what they feed on?
That is part of the problem. The sponges on the photographs are probably from the calm waters of a lake or dam, or from slowly streaming water. Sponges of the same species can take very different body form, depending on where they live. Under conditions of strong current, they will grow encrusting, mat-like or lumpy. Living relatively close to the surface many species are green because of symbiotic algae; in deeper waters, in caves or under stones specimens of the same species are without algae and will be yellowish or brownish.
Taxonomy of freshwater sponges of Maharashtra, India, with illustrated descriptions and notes on ecology and habitats (Porifera: Spongillida: Spongillidae)
You need to study spicules and gemmules to id a sponge...you can see our papers........if you have already done that ...what species do you have?? may I know??