Is there a way to tell the difference between 1 and 2?
Location as above is one way.
1.) Generally if the program is university based, but matches lots of IMGs, it's usually location. Any program with an .edu email, primary affiliation with an academic hospital and medical school and you should be assured there have to be some good faculty members there.
2.) If a place has invited the whole internet, the website shows majority IMGs, and everyone seems to have been invited for an interview, that's a sign of a potentially malignant program.
3.) Generally Carribbean students specifically (nothing against them personally) are an indicator species of the worst residencies because they'll take any categorical position open to them so if they're a
significant majority that's a sign of a bad program as it means everyone else did not rank them. Key word is significant majority. Carribbeans like every other medical graduate group is heterogenous and some work very hard and deserve to be at decent programs so you shouldn't hold it against a program if they have 2-3 Carribbeans in a class of 10 for example if there's a mix. Now if it's 9 Carribbean students and 1 DO, that's different.
4.) Generally IMGs from Europe+Commonwealth/South Asia/Middle East/Islam-Dominant African countries are solid/ambitious residents. They may get ranked below US MDs but they are solid nonetheless and have other options.
5.) Unrelated point but HCA residencies are terrible. They have the veneer of a respectable program and recruit 230+ but the quality of supervision and mentorship is absolutely terrible.