Thai curry and (the majority of) Indian curry are massively different. Thai curry is merely OK if there's nothing else, but lots of Indian curries are great. Actually, what you get in the UK isn't really Indian curry a lot of the time. Some of it is, but lots of it is very Bangladeshi influenced and lots again is quite Anglicised by turning drier curries into creamier ones (eg Chicken Tikka Masala).