Oh, the difference between a 'wireless access point' and a router is that technically the access point is supposed to be a bridge between a network and a network of WiFi devices. A wireless AP is supposed to hook into a router since the router is to provice DHCP services.
I think most will agree that 'access points' have become somewhat of a marketing keyword now. I used to have an Apple AirPort which is an 'access point' but it had DHCP services.
Here is a better link I found than my stumbling for explaination:
Access point vs routers