GP=general practitioners and PCP=primary care physicians are the same here. It is just a matter of personal preference for what you want to call them.

I haven't seen the acronym IM MD used very often but most Internal Medicine Doctors serve as GP's and PCP's. Anyway, they are all basically the same.

Doing away with all acronyms in medicine is starting to be implemented in favor of spelling everything out. There are too many acronyms which can cause confusion and the potential for medical errors.

PCP is a good example. Depending on the context you might have to guess if someone means the drug or the doctor. Sometimes it isn't easy to decipher medical records.

Medical research papers are the worst for making up acronyms.