Allow me to set up an example. We have a 50 inch 1080 TV next to a 4K TV that is the same size, both showing the same picture, but each at their native resolution, and we're ignoring all other things related to picture quality. We're standing 3 meters away from the TV's, and for the sake of the argument, we are facing both TV's head on. At this distance, it is physically impossible for most, if not everyone, to see individual pixels. As such, if we ignore any other picture related features, we essentially see the same picture. The picture on the 4K TV is technically better, but our eyes can't perceive it.
That's all resolution is. It's a greater collection of pixels. 4K TV's do have features that result in significantly greater picture quality, but if you intend to sit at a distance where it was impossible for you to tell apart the individual pixels on an equal sized 1080 TV, then the added resolution on a 4K TV won't matter. The other features can still make it worthwhile though.
If you, or anyone else, know something about resolution that I don't, then feel very free to educate me.