AMD has always touted theoretical performance and compute. Those thinking the 480 is more powerful than a 980 are ill informed. 480 has been assimilated to the 390, which isn't worlds apart but its nowhere near between a 980Ti and 980.
AMD's theoretical TFLOP performance has never matched the competition's real game performance. Tflops is not a measure of games performance.
R9 290 2.5 yrs ago came with 4.84 TFLOPS...only to be routinely bested by the GTX 970 with 3.9 Tflops. Driver overhead and architecture speed plays a larger role, and now Pascal's IPC is faster in comparison due to the higher clocks.
PC I i7 3770K @4.5Ghz I 16GB 2400Mhz I GTX 980Ti FTW
Consoles I PS4 Pro I Xbox One S 2TB I Wii U I Xbox 360 S