>>27450The only way to distinguish them is the intent with which they were created. Any time a board is created it's (ideally) because another board had too many threads getting bumped by a particular topic which is then moved to its own board. A containment board is created because a board (but usually multiple boards!) has too many threads getting bumped by a particular topic that is widely regarded to be absolute fucking cancer.
The split of /a/ and /jp/ is a good example of a board being created. /jp/ isn't cancer, it's just content that didn't fit on /a/ and Touhou. /mlp/ is a good example of a containment board. Horsefuckers shitted up every board they could until everyone got sick of them and exiled them to a containment board.
The containment boards are /mlp/ /soc/ arguably /vg/ arguably /pol/ arguably /adv/