These are various radio services available depending on the intended use. While I am not an expert in what the regulations are for each, this may get you started...
FRS= Family Radio Service-low powered UHF radios for short range communications. I believe they are limited to 5 watts and that use of external antennas is prohibited. They are not intended for business application, and that may well be prohibited by regulation. Requires no license.
GMRS= General mobile radio service-operates also in the UFH spectrum but with higher power limitations. 50 watts max. Use of external antennas is allowed and there are various areas served by repeaters. I am not sure, but I think these can be used in business applications as well as personal. FCC licensing required.
Business band is exactly what is says. This is a service intended for business use. I am not sure what regulations are in place, but i do know that licensing is required.
The FCC website provides all information pertaining to these services. Go check it out if you are interested. Just google one of the services and you can get a lot of good info.