What is the difference between sanitizing, disinfecting and sterilizing?

I bought a Shark steam mop and have been using this to clean my floors. It claims to "sanitize floors" so I haven't been using floor cleaner (used to use antibacterial Mr. Clean and a reg mop) Now i just sweep or vacuum and use the Steam Mop.. are my floors really clean?? These words confuse me.. are sanitize, disinfect and sterilize all the same technically?