What is the difference between galvanized and stainless steal bolts?

Most of the answers you've gotten are correct. However, having been a construction specifications writer and a construction inspector, it all depends on what was written in the installation contract. If stainless steel fasteners were specified, it's simple - call the contractor and demand that stainless fasteners be used. However, if there were no specifications given for the fastening system, you may have to either accept the galvanized fasteners or negotiate a price with the contractor to return and replace the galvanized with stainless. "Caveat Emptor" (Let the buyer beware).