Relevant excerpts from each, emphasis mine
18 years ago
GFDL:
A "Modified Version" of the Document means any work containing the
Document or a portion of it, either copied verbatim, or with
modifications and/or translated into another language.
4. MODIFICATIONS
You may copy and distribute a Modified Version of the Document under
the conditions of sections 2 and 3 above, provided that you release
the Modified Version under precisely this License.
CC-SA:
"Derivative Work" means a work based upon the Work or upon the Work and other pre-existing works, such as a translation, musical arrangement, dramatization, fictionalization, motion picture version, sound recording, art reproduction, abridgment, condensation, or any other form in which the Work may be recast, transformed, or adapted
You may distribute, publicly display, publicly perform, or publicly digitally perform a Derivative Work only under the terms of this License
FA:
The By You/For You Policy
The By You/For You policy is the heart and soul of Fur Affinity’s rule system. It’s simple and to the point: if you didn’t create it or if it wasn’t created specifically for you (gift/commission) then the Submission can not be posted.
Further clarification of the By You/For You policy is broken down into two sections (For You and By You) for easier clarification.
1) By You:
You may freely post any submission so long as you created the content and said content abides by all other rules of the site.
Hi.
A "Modified Version" of the Document means any work containing the
Document or a portion of it, either copied verbatim, or with
modifications and/or translated into another language.
4. MODIFICATIONS
You may copy and distribute a Modified Version of the Document under
the conditions of sections 2 and 3 above, provided that you release
the Modified Version under precisely this License.
CC-SA:
"Derivative Work" means a work based upon the Work or upon the Work and other pre-existing works, such as a translation, musical arrangement, dramatization, fictionalization, motion picture version, sound recording, art reproduction, abridgment, condensation, or any other form in which the Work may be recast, transformed, or adapted
You may distribute, publicly display, publicly perform, or publicly digitally perform a Derivative Work only under the terms of this License
FA:
The By You/For You Policy
The By You/For You policy is the heart and soul of Fur Affinity’s rule system. It’s simple and to the point: if you didn’t create it or if it wasn’t created specifically for you (gift/commission) then the Submission can not be posted.
Further clarification of the By You/For You policy is broken down into two sections (For You and By You) for easier clarification.
1) By You:
You may freely post any submission so long as you created the content and said content abides by all other rules of the site.
Hi.