Here's a quick comparison between the two GPUs to give you an idea in the performance difference.
Crysis 2, max settings DX11, 1080p, high-resolution textures, 4xMSAA
http://www.guru3d.com/miraserver/ima...ntitled-19.png
7850: 42 fps
7770: 25 fps
Battlefield 3 DX11, Ultra mode, 4xMSAA, 16x AF enabled, HBAO enabled
http://www.guru3d.com/miraserver/ima...ntitled-28.png
7850: 32 fps
7770: 21 fps
Crysis 3 1080p, DX11, High settings, FXAA:
http://www.guru3d.com/articles_pages...nchmark,6.html
7850: 35 fps
7770: 23 fps
Crysis Warhead 1920x1080 - Enthusiast Quality + 4xAA:
http://gpuboss.com/graphics-card/Radeon-HD-7770
7850: 38.9fps
7770: 23fps
Tomb Raider, 1080p, Ultra, DX11:
http://kotaku.com/5990848/tomb-raide...phics-and-cpus
7850: 42 fps
7770: 29 fps
Metro 2033, 1080p, Max, AAA, DX11:
http://www.guru3d.com/miraserver/ima...ntitled-17.png
7850: 27 fps
7770: 15 fps
Based on the above, PS4 games should certainly look a lot better, or their performance should at least be superior.