The RB411AR is has a built-in 802.11 b/g wireless card with a sturdy MMCX connector, and a spare miniPCI slot for another wireless card.
RB411AR includes RouterOS - the operating system, which will turn this powerful system into a highly sophisticated router/firewall or bandwidth manager.
The RB450G is a five port Gigabit ethernet router. Comparing to the RB450, the RB450G not only adds Gigabit speed capability, but also 256Mb of RAM, a faster CPU and a microSD card slot for file storage.