Lead Trombone: is also the section leader and has an assured upper register. They are also probably the most experienced and sophisticated musician in the section.
Second Trombone: is often the player that does the most improvised solos. Both Lead and second often require smaller equipment to blend better with the upper voices of the Brass.
3rd & 4th Trombone: are the workhorses of the section and often use larger bores. Fourth Trombone is often the Bass Trombonist’s chair (as opposed to Tenor).