They see how the universe really works. The two types work together, The theorist uses experiments to see if they are computing things properly, and the experimentalist uses theory to find out where the problems lie and what problems need to be worked on. We can further differentiate much research into 3 categories 1. Basic Research, 2. Applied Research, 3.
Basic research is the study of how the world works in order to understand it, nothing more.
Knowledge for its own sake. Most of this is done within the university environment. Applied Research is the study of things that may be used to better mankind. For instance, how lasers work. Technology is the application of research for commercial or industrial goals.