linuxmemes

IMO both of these ended up being poor names.

"Open source" can be co-opted to mean any project with public source code even if it's not open contribution (think SQLite, and many of the projects effectively run by major tech corporations).

"Free software" falls victim to the eternal mixup with freeware, requiring the endless repetition of the "beer vs. speech" analogy.

I personally think "Libre software" is the term that best encapsulates the intended meaning while being unambiguous and not vulnerable to misinterpretation.

Open Source: The source is available to inspect for security issues and can be improved upon by anybody who wants to participate. Most of the times the software development is financed by donations in cash from users or in time from developers.

Free software: Software you get for free, usually paid for by siphoning off data, running ads (which include trackers), ... sometimes open source, most of the times closed source.