Yes AR15 lowers and uppers from different manufacturers should match, unless otherwise specified. Some will have a bit more wobble than others, which wont affect performance, but drives some people (including myself) nuts. If you want a tight fit without tinkering yourself, you may want to look at buying a set from the same manufacturer like Aero, or buying a lower with a tension screw.
For .308, I am not sure. I only know there are two different standards with somewhat different parts. I don't know if discrepancy affects upper/lower match.
