The Iconia Tab A200 is Acer's 3rd tablet introduced after the A500. The are both 10 inch tablet that runs Android Honeycomb operating system. Iconia A200 is a bit lighter and unnoticeable thinner than the A500, but both are very similar devices. Acer also sells a seven inch tablet in the form of Tab A100. The A200 has a different physical design than the 1 year old A500. The A200's have rounded corners that are not quite as noticeable as the A500's slightly tapered ones. Also, A200 has a plastic shell vs the A500 aluminum cover.
Acer Iconia A500
Acer Iconia A200
The main differences between the two Iconias is that the A500 have a HDMI port and a rear facing camera. So if you like to take photos or videos with your tablet you will prefer the A500. There is only a $50 difference between the two tablets so it is a matter of preference. Do you want an aluminum feel or a plastic feel? Do you want to be able to hook up your tablet to your tv? Personally, I'm waiting for the reveal of the A700 which will have Nvidia's Tegre 3 Quad Core processor and 1920 x 1200 resolution.