It just depends; there are a lot of steps in making a print between exposure and the final print. With some photos it will be possible to determine how they were made, and with other it won't.
It might be hard to tell the difference between two inkjet prints, one from a DSLR, and one from a scan of medium or slow speed film. It's fairly easy to spot gelatin silver on FB, which the odds would imply is from film, although I think there are people using LED enlargers to print from files on to traditional BW process papers. I think it's totally possible for someone moderately talented with PS to simulate all sorts of film looks with a digital capture.
It would be a fun game, but you wouldn't catch me putting much money down on my ability to determine what the original capture media was.