sustain will depend on your construction with these puppies. But i believe that mahogany has better sustain due to its better resonance.
Tone:
Mahogany: Warm, lots of lows, rounded off high end.
Maple: Tight, quiet low end, screechy extended highs, lots of high mids.
the biggest difference you'll notice is RESONANCE, which is something that nobody talks about. Since mahogany has kind of an open grain, it resonates, vibrates, lives in your hands, it will be a loud guitar to play dry. Maple on the other hand kinda absorbs the sound, makes it a relatively quiet and dry guitar.
Maple is great for necks though because its so goddamn hard that it has trouble warping