Overexposure to ultraviolet light can degrade a garage floor coating. Epoxy can rapidly degrade and fade in the constant presence of ultraviolet light, while polyurethane will remain unaffected by ultraviolet light exposure.
Some garage floor sealants are more prone to scratching. Epoxy is easily prone to scratching and etching. While polyurethane is not immune to scratching, it is much harder to scratch than epoxy.
Epoxy creates a hard surface when applied to a garage floor. Polyurethane also creates a hard surface when applied to a garage floor, but it is not as hard as epoxy.
Often, a coating of polyurethane is applied to the surface of a garage floor over a coating of epoxy. The resulting combination creates a harder surface than could be achieved by using only one of the materials to seal the surface.
Both types of sealants are topical sealants. This means they provide a protective barrier on the surface of a material. Both sealants are durable and curb the rate of degradation of a garage floor. A garage floor will require little maintenance as years pass if epoxy and/or polyurethane sealants are employed.