[rogerbinns]

They both give roughly the same rights and benefits when using items under the license for your own purposes. The difference is when you want to redistribute. GPL says that when you redistribute, you cannot remove the freedoms you received in the first place. BSD says you can remove those freedoms.

GNU & GPL really are about freedom as in freedom of speech. They ensure items cannot get less free when redistributed. BSD etc are more about getting out of your way, so you can do almost anything you want on redistribution.

Copyleft matters to those who care about freedom first. The FSF has a good explanation: https://www.gnu.org/philosophy/free-sw.html

Historically RMS has been seen as a bit of an alarmist over software related freedoms. However the passage of time often shows he isn't alarmist enough! Here is a good starter article from almost 20 years ago http://www.gnu.org/philosophy/right-to-read.en.html