Utility
Neither the Subaru Legacy nor the Altima Hybrid has a marked advantage in terms of seating capacity.
Performance
Regarding horsepower, the Subaru Legacy packs quite a punch and will knock the Nissan Altima Hybrid down a few rungs. However, keep in mind that high horsepower engines often command higher insurance premiums.
Dimensions
The Subaru's tank is about the same size as the Nissan Altima Hybrid's, though the Nissan Altima Hybrid's is a little larger.
The Subaru Legacy and the Altima Hybrid compete for the same parking spaces.
Convenience
The Subaru Legacy's fuel tank will need to be replenished more often than the unit in the Nissan Altima Hybrid.
Cost
The destination charge is a standard charge for transporting the vehicle from its point of origin to the dealer. It costs almost the same to get the Subaru Legacy to the dealership as the Nissan.
The Subaru Legacy will tax your gasoline budget tremendously more than the Nissan Altima Hybrid will.
With respect to MSRP, the Nissan Altima Hybrid costs approximately as much as the Legacy (though the Legacy is a tad cheaper).
The Subaru Legacy will cost you a lots_of_money in gas every year compared to the Altima Hybrid.
Drivetrain
The Subaru Legacy's engine is a bit smaller than the Nissan Altima Hybrid's, but not terribly so.
Torque is the force that lets you accelerate quickly, and in this respect, the Subaru Legacy isn't much more powerful than the Altima Hybrid.
Warranty
The Nissan Altima Hybrid and the Subaru Legacy have the same basic after-sale protection.