48 pixel shaders or no?

hey guys Video card question, theres the Radeon X1800XT 512mb gddr3
and theres the Radeon X1900XT 512mb gddr3. the only differance is that the
X1900XT has 48 pixel shader things that it says it has, and also theres a big price differance between the two cards : X1800XT = 339.00,  X1900XT = 439.00. so I just want to know what the big differance is because the only thing I cpuld find is the 1900 has 48 pixel shaders?

http://www.firingsquad.com/hardware/ati_all_in_wonder_x1900_review/page15.asp

Random review pulled off of google. Both 1800 and 1900 are in it and the 1900 is obviously considerably more powerful, it's the best card in ATi lineup. BTW it's not really worth getting the X1900XT unless you really have to have the best. The 1800 is still perfectly capable of running any game with graphics and AA at reasonably high if not max levels.