Heating and Cooling are the BTU's Measured in a different way?

I have always wondered if heating and cooling BTU's are measured in a different way. I know the obvious one is cold and one is hot but why is the heating always a way higher number the the cooling?

I have a Frigidaire Window AC unit that could have had a heating option (I believe electric resistance heater and not a heat pump) while the cooling BTU is 8,000 the heating would have been 9,500 BTU



Thanks

Heating and Cooling are the BTU's Measured in a different way?