They are the same device, except that the 3750 can stack and be managed as one large virtual switch (up to 9 3750s can stack, and appear as 1 switch with 9 modules).
The nice thing with the 3750s is you can do etherchannels across switches in the stack easily, as well as QoS across the stack/etc.
Both devices have 32gbps switching fabric, which means you are oversubscribed at 48 1gig-e ports. They will both support multicast on the LAN.
If you look at the 3750X and 3560X switches, these have 160gbps switching fabric and double the memory of the 3750/3560 devices.
Hope that helps!
Tim