Loo x Water Closet x Closet x W.C.

Hello, dears.

I looked at Vocabulary.com (such a reliable dictionary) and onto it I found out that water closet, W.C., closet and loo had all the same exact meaning: a toilet in Britain.

So, I wonder whether there is or not a difference between these words, grammatically or no difference? Please, I'd really appreciate your help. (And by the way, I do recommend you that site).

Regards.