Here's a quick look at the specification:
You can check out the rest of the slides at VideoCardz.
AMD Radeon RX 580: Polaris 10 GPU with same number of cores, TMUs and ROPs as Radeon RX 480. Base clock increased from 1120MHz to 1257MHz, and Boost gets a bump from 1266MHz to 1340MHz. Memory configuration remains the same (4/8GB GDDR5), just like the identical 8000MHz memory clockspeed.
AMD Radeon RX 570: Based on the same Polaris 10 chip as the Radeon RX 470 but with a base clockspeed increased from 926MHz to 1168MHz, and a new Boost frequency of 1244MHz instead of 1206MHz. This card will also ship in 4/8GB GDDR5 memory configurations, and AMD increased the memory clockspeed from 6600MHz to 7000MHz.
AMD Radeon RX 560: This is a fully-fledged Polaris 11 chip. While the Radeon RX 460 had 896 stream processors, 56 TMUs and 16 ROPs, this new model has 1024 cores, 64 TMUs and 16 ROPs. Clockspeeds are also up to 1175MHz base and 1275MHz Boost, while memory specs remain the same.
AMD Radeon RX 550: This model uses the new Polaris 12 low-end GPU. It has 512 stream processors, 2GB GDDR5 memory and a 128-bit memory bus. Boost clockspeed is 1183MHz.