Mesh networks or ad-hoc networks use the hardware differently - hardware can be mobile or their roles (providing access to other networks like the Internet) change. Instead of hierarchy with a router in master mode (AP) and a client in station mode the nodes in mesh networks are more similar to each other.
Many mesh networks don't work on the fly because they need software to manage routing (OLSR,BATMAN) or service advertisements (zeroconfig).
mesh.80211s : P2P , P2PGO
mesh.olsr : community: Freifunk
mesh.batman : community: Freifunk