While archives, museums, and libraries share many common principles, they operate very differently and provide very different experiences to their guests.
Libraries: Public-facing resources for a broad audience on many topics; able to browse and borrow materials; collection consists of widely-published items
Museums: Public-facing displays on select topics; able to browse exhibits (some of which may be hands-on); focus on collecting unique physical artifacts
Archives: Research-oriented on specific topics; collections not on public display; available by appointment; materials can not be borrowed; focus on collecting unique records