200 series - This budget, entry level lineup includes the nuvi 200, 250, 260 and 270. All have a 3.5" screen. A relatively new series, these units have an internal antenna, giving them a less obtrusive profile.
200W series - The 200W and 250W are also entry level units with limited features, albeit with a 4.3" screen.
300 series - With more features than the 200 series, this set includes the first two nuvis ever released, the 350 and 360, along with the newer 370.
600 series - More feature laden still, this line includes the nuvi 650, 660, 670 and 680.
700 series - The newest additions to the nuvi family, these units incorporate the high-end features of the 600 series, with the internal antenna found on the 200 series.
x70 models - The tranatlantic 270, 370, 670 and 770 models have maps of the U.S., Canada and Europe.