House Bills and Resolutions: A bill originating in the House of Representatives is designated by the letters ‘H.R.’ followed by a number that it retains throughout all its parliamentary stages.
Senate Bills and Resolutions: A Senate bill is designated by the letter ‘S.’ followed by its number
Joint Resolutions are designated H.J. Res. or S.J. Res. and are followed by a number. They become law after approval by both houses and the President. There is no practical difference from bills, but joint resolutions generally deal with more limited matters.
Concurrent resolutions, are designated H.Con. Res. or S.Con. Res., and followed by a number. They deal with matters that affect the operations of both chambers and must have both chambers’ approval, but do not require Presidential support.
Simple resolutions are designated H.Res. and S.Res., followed by a number. A simple resolution addresses matters entirely within the prerogative of one house.
Find more detailed information at the United States Senate website.