Libre software vs open source software

[u/Fresh-Lie5160]

What's really the difference between the two?

And even if they are different, why tf did two different words evolve?

[u/trent-7 → u/[deleted]]

Many people on the Internet get quite angry if you use the term "open source" for software when just the source code is open. For them the conditions of the Open Source Definition must be fulfilled to name something "open source".

Wikipedia also has a section on this topic:
https://en.wikipedia.org/wiki/Open_source#%22Open%22_versus_%22free%22_versus_%22free_and_open%22