Even though I am a film student, I am not all that clued up on the technology, but here it is as far as I understand it. Apologies if there are any mistakes.
Firstly, you probably would be able to tell the difference between something shot on film and shot on digital even when converted to digital projection, because of the difference in things like grain between film and digital. This varies hugely though as some film stocks are grainier than others, but for an obvious comparison compare the look of The Godfather vs Public Enemies. Movies on similar subjects with a vastly different look based on the way it was shot. In a digital projection of The Godfather you would still keep that classic film look.
Regarding the resolution, since the advent of HD digital cameras the quality and resolution have approached that of 35mm film, and at this point I think the technology, such as the Red camera are able to deliver the same resolution as 35mm. As for 70mm, as far as I know the resolution would be much higher than the digital cameras used today. The Red One camera can shoot at a resolution of 4K, significantly higher than say your BluRay resolution, but still roughly similar to 35mm film.
The pros and cons of digital will continue to be debated for some time to come I think. At this point I think it is mainly an aesthetic debate, as the practicality and economy of digital has been well proven. There is a difference in the look, and many, myself included like the look of celuloid, but I think that this sort of thing can now be digitally simulated, so digital as the standard is probably not far away.