Logic, Mainstage and GarageBand use the same architecture. They share (among others) the same
- Settings (Plug-in Settings and Track Settings)
- Instruments (some)
And they are compatible in many other ways.
The Loop Browser is almost identical in GarageBand and Logic. They display the same popup menu for the installed Loop Libraries.
When you create a new Loop in GarageBand, it will be available in Logic in that popup menu and vice versa. The reason is that they acess the same index file. This is like a database that contains the information of all the installed Apple Loops.
Here is a digram of that principle.
I explain more in my new Garageband Manual "GarageBand 11 - How it Works"
I also wrote a free manual about the whole topic of Apple Loops in 2005. It is a free pdf dowload available on my website;
Hope that helps
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