Bug spray is a chemical in a spray can that is used for killing bugs or keeping them away.
Some bug sprays are sprayed at the bug to kill it. Other bug sprays are sprayed around a house or picnic area. Bugs that come too close to this kind of bug spray will usually die.
Bug repellent is never sprayed at a bug. Bug repellents can be used to keep bugs from coming into a house or picnic area. Some kinds of sunscreen have bug repellent that keeps mosquitos away. Some bug repellents are spread over the skin of a person.