When you have two versions of anything, it usually means that one of them has at least some sort of restrictions or lacks some features. That's most likely the free version.
Yes, you do have a free version called ''Community'' and a paid one called ''Enterprise''.
The community one is a free, open source but it requires you to know what you're doing. If you're a complete beginner then this isn't a good fit for you.
There are a few key differences between the two such as;
- the loading time of the pages (obviously paid is better),
- faster indexing,
- the free one isn't good if you have many products,
- free one doesn't have full page caching,
- and more.
The Magento Community can be fine if it meets your needs
some people just want more and therefore go for the Enterprise. I hope that this helps!