Mark, despite what is written above - yes you can count and log those hours. But - like anything in life it isn't a simple matter.
Firstly, if you have a work visa ( H, L, E etc) then you are lucky and you should definitely take advantage of the fact that you have the unambigous right to undertake flight training whilst in the USA ( subject to TSA approval) . If you are already there its cheaper and more accessible and straightforward than just about any other country.
However, whether or not you get a private certificate whilst you are there, the hours you log won't count 1:1 for what you need to do for an EASA PPL. The syllabus and training and requirements are structured differently. The hours won't be wasted but won't be completely helpful either. What you will get is experience and useful perspective and both of those will really help with the EASA route should you later do that. Some of the hours will be directly creditable ( for example towards total hours flown) but some won't be so useful ( night dual will count for dual time but no need for specifically night dual for easa). The written exams are of no convertible use but the knowledge gained whilst taking them is invaluable.
Ultimately, if you want an EASA PPL - study for that and regard the USA flying as valuable preparation and experience and orientation with some hours creditable. Or go for the FAA private and get it done and expect to spend another 20 hours and the EASA writtens and flight testing if you want that too.
But - don't waste the opportunity to use the work visa to get some US flight training done
Hope that helps...