A warranty is a specific type of guarantee. It's defined as a promise to a consumer that a manufacturer will make any repairs or replace defective parts without additional charge during a stated period of time.
A guarantee is defined as "a promise or assurance, especially one in writing, that something is of specified quality, content, benefit, etc., or that it will perform satisfactorily for a given length of time." While a guarantee assures the quality of an item, a warranty promises performance of any repairs that item may require. A warranty is commonly offered to those who buy automobiles and electronic appliances.