> So, the main difference between GPL* and CC-* is that CC always require
> the inclusion of the credits, while GPL does not, correct?
I am not a lawyer. This is not legal advice. This is a difficult topic,
I learned a lot about it and also contacted cc, but I could still be wrong.
No, they both require attribution.
(Corner case: Unless some special "no attribution required clause was
added". I've seen that for CC, not for GPL.)
GPL is always SA (share-alike) or in GPL jargon (copyleft), i.e. it must
always remain under that license. (Corner case: The copyright (creator)
holder releases under a different license.)
Only summary: There are many CC license and they are quite different.
From most permissive (CC0), to attribution only (ex: CC BY) to share
alike (copyleft) (ex: CC BY-SA) up to proprietary (ex: CC BY-NC-ND
(Attribution Non-Commercial No Derivatives)).
I mailed CC BY and asked... Using something under CC BY, you could:
1. take something licensed under CC-BY
2. make a derivative work
3. attribute the original work
4. distribute the derivative work under CC0.
So what's the difference between GPL (x) and CC BY-SA?
- License compatibility.
If you ask me, the law is broken. All license incompatibility comes from
outdated laws. For example, I'd like to release my documentation
compatible under GPLv3+ and under CC BY-SA (+?). I could dual license
it, but if someone forks it exclusively under CC BY-SA and I want to
include the improvements, I would have to drop GPLv3+, otherwise I
weren't allowed because they are incompatible. Therefore for now I stick
with GPLv3+ and act as copyright proxy. If anyone needs it under a
different license we work something clever out to remain compatible.