pull down to refresh

I do suspect the map is incomplete. Reachable nodes are very likely to be in the minority of nodes given the way routers work - it requires additional configuration explained here https://bitcoin.org/en/full-node#enabling-connections.
Listening and reachable mean the same thing in this context - they accept/listen/can receive incoming connections from peers. In contrast, unreachable/non-listening nodes establish only outgoing connections to peers.