Finally-- some real specs to highlight the differences.
http://www.kitguru.net/apple/anton-shilov/apple-makes-imac-with-5k-retina-display-more-affordable/
http://www.kitguru.net/apple/anton-shilov/apple-makes-imac-with-5k-retina-display-more-affordable/
The affordable Apple iMac 5K (with 5120*2880 screen resolution) is based on a quad-core Intel Core i5 processor with 3.30GHz clock-rate and is equipped with AMD Radeon R9 M290 2GB graphics adapter (Bonaire XTX, 896 stream processors), 8GB of DDR3 memory, 1TB hard drive, two Thunderbolt 2 connectors, four USB 3.0 ports and so on.
The m290x in my machine has 1280 stream processors. The BTO m295x has 2048 stream processors. The trick is finding a benchmark that translates these technical differences into "real world" data, and some benchmarks-- cinebench, for one, don't really highlight the differences that you might see in the latest generation of games.