It’s generally all about the BTU’s. Years ago propane farm tractors were available. But if for example you bought a 70 JD LP it would have maybe 8 less HP than the gas version. If you had the rare 70 diesel, that had more power than either the gas or the LP.
Same with running #2, a fuel blend, or #1. The HP, and in the instance of road vehicles the mileage, decreases with the increase in the ratio of the #1 fuel. Noticeably!