First there was Radeon-256 (now named 7200). One output, two rendering pipelines. Then came Radeon VE (now 7000), two outputs, one rendering pipeline - slower, but you get dual head capability.
Then there's 7500 which is faster and has both a non-castrated 3D engine and dual head capability, and also doesn't need a RageTheater companion for TV-out. All the "LE" and other flavors are the same thing, clocked slower or faster, with various RAM configurations (128-bit SDR or DDR, 64-bit DDR, clock reduced fanless versions etc. etc.)
8500 is the latest and greatest, with a variety of cards like with the 7500 series.