Why the difference in Fare?

[BuffaloJoe]

I noticed that First Class on the PHL-LAS route has a fare of $614 each way on HP and $1234 on US. I did not book first class, but this made me think what is the difference between HP 1st Class and US 1st Class (Besides the price)? Is there anything different besides more seats?

 

[flyingcat]

Different types of first/coach class fares in varying buckets. The US flight probably has few F seats left while the HP flight is wide open. All filed fares are combined there are no longer seperate fares filed between the two carriers.

Fare available on US operated by HP
AA0UPN A X 834.00
Fare available on US flight
YUP6 F X 1234.00

Both are very different in terms of fare rules. The A fare is not an actual first class fare. It is a coach fare that is upgradeable at time of purchase. It is rare but there have been circumstances where A fare customers do not get an upgrade. They have no recourse since by definition it is a coach fare.