It will probably matter to you only if you can't accept anything other than the original mix. As a familiar example, Steven Wilson has done the remixes on a bunch of classic prog albums recently. It's kind of a toss-up. I still like the original mix for King Crimson: Lizard, while the new mix sounds a little dry to me. I think SW missed some of the dynamic cues of the original mix when he did Larks' Tongues, but the gritty distortion from the original mixdown is now mostly gone. And some of those 'alternate' mixes are quite interesting. But in most of these releases you can hear both renderings right in the same package, which is very cool.
A remaster, in the digital age, has just become a way to repackage the original mixes, usually of a classic album that is probably a couple of decades old, and often with a large caption on the front that says "Newly Remastered" so that you might think it's something you don't already have. You might notice some sonic manipulation on the remaster, but hopefully it was done judiciously, with the best sources and technology available. But I don't think it's ever just a straight transfer...which might not sound as good as you'd expect, in some cases.
