There's not a big difference. The major difference is (after 9 AM
IIRC) there is complimentary beer and wine served in coach. Liquor is still for purchase in Y, free in F. There are also dedicated shuttle ticket counters, gates, and security lines.
Since the shuttle is no longer a separate division in the company there isn't really anything branded as US Airways Shuttle anymore. The aircraft are swapped between shuttle and mainline ops as well, so everything is just standard US on the aircraft.
It's a great product, though. Many of the FAs have been flying the shuttle for years and it's a pretty pleasant experience.