Hereâ€™s a great shot from China Defense Blog of Chinaâ€™s J-20 stealth fighter alongside Russiaâ€™s Sukhoi PAK FA and the American F-22 Raptor.
Iâ€™m no low-observable design expert, but the undersides of the Raptor and J-20 look a heck of a lot cleaner than the Russian jet. This fits reports that the jetâ€™s design trades stealth for increasedÂ maneuverabilityÂ compared to the F-22.
Also, whereâ€™s the space for the internal weapons bay on the PAK FA; between the engines, forward of what looks like an aft-EW suite? Itâ€™s been reported that the weapons are carried there and in the two bulbs that can bee seen next to the air intakes.