No that's something else, LoROM and HiROM differ in how the ROM data is mapped into memory, while FastROM and SlowROM differ in the bus speed. You can have Lo/Slow, Lo/Fast, Hi/Slow or Hi/Fast carts.

They're related but not the same. This wiki page explains LoROM and HiROM; FastROM is explained by this sentence.

> Different address ranges are accessed at different speeds, and the speed of the ROM at banks $80-$FF may be changed with register $420D.

https://snes.nesdev.org/wiki/Memory_map