An Access Point is a simple wifi device, normally used in commercial setups, that it's only job is to be basically a Wifi switch, take a LAN connection and allow it be accessed by wireless devices. Consumer devices tend to have multiple roles, Router, Modem, Switch. Now an Acess Point needs a connection to the LAN, in normal situations this is done by a network cable.
Mesh technology utilizes the wireless uplinks to expand networks even further and have no set path back to the main point. Newer access points utilize this method to increase wifi coverage in both consumer and commercial setups. You usually have one main point that is connection via LAN by traditional cables, and nodes connect to the main point wirelessly, only requiring power instead of a dedicated line.