@lxo there are more (different) software licenses that you can count on your hands, some with super different rules of how you can use (and also use as a reference or copy) those softwares...
You can aways check the internet to compare 'em, and there are big differences even between more "relaxed" ones, when it comes to software we use daily on a gnu/Linux or just Linux (call it what you will), or BSDs, etc etc etc...
Like Creative Commons, GNU, Apache, MIT... And so on...
Gotta compare em, each of, to see what you can and can't do with that software (or part of it), and, also, if you can or can't monetize it, if you use other pieces/sets of software from an specific license...
As I've said on another post, i just hate Copyright and things related to it, like patents... But, that's why (also) software sites usually have a lawyer or a team of lawyers working for em...