Although currently limited only to China, as we did not find it listed anywhere in Europe, the Radeon RX 580 2048SP SKU has 32 CUs, 2048 Stream Processors, 32 ROPs and 128 Texture Units, which makes it more similar to the RX 570, rather than the RX 580, which packed 36 CUs, 2304 Stream Processors, 32 ROPs and 144 Texture Units.
The only difference between the regular Radeon RX 570, available worldwide, and the RX 580 2048SP is the Boost clock, which is pushed from 1244MHz to 1284MHz. The base clock is the same at 1168MHz.
With the upcoming launch of the 12nm Polaris refresh, AMD is probably looking to make a wider performance gap, as the so-called Radeon RX 590 would have even higher performance gain over the RX 580 2048SP.
The RX 580 2048SP 4GB version was spotted in retail in China with a price of yuan 1349.00, or around $195/€170. It is highly unlikely that the RX 580 2048SP will launch outside China.