I got two quotes for installing split A/C system for the 1200 sq ft second floor of our house in Massachusetts (the first floor already has it). The two quotes are over $2500 apart, but they don't compare apples to apples. The first was a 2 ton Carrier system:

Brand: Carrier
Condenser: Comfort 16 (Model 24ABC6)
Air Handler: Fan Coil FX4 (Model FX4DNF025)
Capacity: 2 ton (24,000 BTU)
1 Central Return
Cost: $8,130

The second, more expensive, was a 2.5 ton American Standard system:

Brand: American Standard
Condenser: Gold XI Allegiance 15 (Model 4A7A5030E1000A)
Air Handler: Platinum XV (TAM7A0B30H21SB)
Capacity: 2.5 ton (30,000 BTU)
2 Returns: 1 Central, 1 in Master BR
Cost: $10,715

The second offers a 0.5 ton higher capacity, but also appears to be for more more premium equipment. It also has more involved labor, as it provides for an additional return. Any idea how much these factors are contributing to the higher cost and how much is due to the second contractor simply charging more? Any other opinions on these options?

Thanks!