Scoutmaster (SM) / Assistant Scoutmaster (ASM)- these Scouters work closest with the Scouts and ensure the program is running as it should. Their primary focus is to support the Senior Patrol Leader and Assistant Senior Patrol Leader by guiding them in leadership of the Troop while delivering the "Program".
Merit Badge Councilor (MBC) - a MBC works with Scouts on an individual basis to work on the specific badges (from 1 to 140) that the MBC is registered to teach. A MBC works with the Scouts "on demand" when he is contacted by the Scouts requesting time to complete badge work.
Committee Member - the role of the committee is to provide the Scoutmaster with the support needed to deliver the program that the Patrol Leader Council chooses as the "Program". The Committee provides the logistical support (funds/fund raisers, camping equipment, Treasury, camp site reservations, recording advancement, Boards of Review, registration/recharter, etc) needed to support the Troop. The Committee also has the responsibility to ensure that the Scoutmaster and the PLC are delivering a program that is aligned with the BSA Charter. If not, the Committee can recommend replacements. The Committee Chair would report to the Charter Organization which has the authority to hire/fire adult leaders.
The Committee is headed by a Committee Chairman who functions as the "great organizer" to make sure that sub-committees are on-task in their roles within the troop, such as ensuring a Treasurer delivers a Treasurer's report... Outdoor Chair is making campsite reservations.... Quartermaster is maintaining the camping equipment.... webmaster(s) are updating the website... etc. To avoid "power plays" the Committee Chair is more of an "organizer" than a "position of authority". Committee decisions are made via parliamentary procedure and voting. The Committee Chair does not get to cast a vote unless votes are tied. By design, the Scoutmaster and assistants are NOT members of the Committee, and therefore cannot vote on committee decisions.