香皂 vs. 肥皂: What's the difference?
The difference is exactly as the definitions say. 香皂 is "scented soaps", while 肥皂 is just generic "soaps". That is the only difference. 香皂 is abbreviated from 香肥皂, meaning soap with added scents.

You can use either for washing face, body, hand, or clothes, but normally people use 洗衣粉/精 for the latter.