The Giant is actually a few steps up in drivetrain/derailleurs. The Cannondale uses the Altus derailleurs and is a 24-speed where the Giant has Deore components and is a 30-speed.
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Shimano mountain bike type Derailleurs from low to high:
Tourney
Altus (what the Cannondale uses)
Acera
Alivio
Deore (What the Giant uses)
LX
XT
XTR
The Giant also has a front shock with more travel and a little bit wider tires. Both bikes have lockouts on the shock, and both use the same Shimano hydraulic disc brakes.
On paper I would go for the Giant. That being said, I think you should ride both to see how they each feel for you. Also take into consideration which one you like the looks of better too.