I've recently downloaded a few DOS games and I'm confused about something.

Very few games come in either a zip or rar file that have maybe 100+ files in them. These kind obviously don't have to be installed. You just extract them to a folder and you're pretty much ready to go.

Most of the games come in a zip file that has maybe two to eight files in it, one of which is an .exe file.

What is the difference in these? I just don't understand why you would do it two different ways.

Are the ones that have the .exe file actually being installed on the computer or are they just sort of being uncompressed? The only reason I ask is because I don't like to install stuff on my computer unless I know exactly what it is.