What are the unique characteristics of a baritone or trombone that set them apart from other brass instruments?

Baritones and trombones are unique brass instruments due to their slide mechanism, which allows players to change the pitch smoothly and continuously. This feature sets them apart from other brass instruments that use valves to change notes. Additionally, baritones and trombones have a rich, mellow sound quality that distinguishes them from other brass instruments in the orchestra or band.