Gaint – make everything, for everyone. Okay, that’s massively over stating it, but they do make a lot of frames for other brands.
But they don’t do the R&D or Design, and frnakly the marketing that makes the badge ‘cool’ just the manufacture – so a Trek for exmaple isn’t a Giant in all but name.
There are a few generic frames about, but they’re fairly rare – if you buy a Gaint, Intense or whatever – that’s what you get.
There are a few different suspension designs thare are shared.
If you look at Intense frames, you may notice they have an awful lot in common with Santa Cruz for exmaple. The Tracer is very Bronson like, with Geo somewhere between a Bronson and a Nomad.