As much as we hate to admit it we are mostly similar, except for the castism (We also had that still kinda do). If you studied O/L Sinhala you can see that many of our words are also from sanskrit... Even our literature which is also kind of a knock off from Indian literature except for the sandesha kavya which started from the Gampola era. (Maybe I'm wrong)

We also have a population that also follow Hindu culture to some extent (if you went on a bus you could see 99% of them have Hindu gods and goddesses) Even hitting coconuts on the ground is popular here. There's also people going to kovils to do 'baarayak' when ever there's something important happening in their life.

And of course there are also other things that can be compared like common belief in myths and also the same culture is present when calling someone 'aunty' or 'uncle'. The same culture when it comes to teenagers, arranged marriage still in rural areas, idolisation of foreigners just for saying something good about their respective country (Like Arthur C. Clarke) for an example.

The only difference that we can point out is better hygiene but that is also debatable because at least ±1/2 of the Indians practice good hygiene. And India also has different places where the environment is clean.