I keep seeing conflicting information of these 2 words. Some websites say mesmo is more BP and próprio is more EP and some say they’re both equally used in both BP and EP.
Whenever I use DeepL which seems to be orientated around EP, I’ve never seen it use mesmo. Eg, próprio o fiz, próprio comprei a casa, but some European Portuguese people have told me they use mesmo. Does it depend on where you are in Portugal?
@reececox2000, I would say that próprio is the most used word in European Portuguese, but mesmo is also a perfectly acceptable alternative, wherever you are in Portugal 
To add to this question. When using this in a sentence it is not clear to me if these words are interchangeble. ex: Fizeram isto a vocês mesmos, could I also say Fizeram isto a vocês próprios, and if so, are there examples where I can’t use mesmo/próprio interchangeble?
@andy_vander_vlist, yes, they’re interchangeable when used like this
Thnx Joseph!