The Samsung is cheaper because it uses a projection system called "DLP" (stands for "Digital Light Projection"). It provides a lower-priced panel, BUT, if you view it at an angle greater than about 20 degrees, the picture dims. On the Sharp, an LCD, the picture doesn't dim at an angle so much as it abberates -- black levels go down, colors can go all funky, and there may be some dimming there, too. All in all, the Samsung should have good PQ, though I haven't seen it in person, yet.
The Sharps have been known to have banding issues, so buyer beware. I don't know if they have 10-bit processing/panel (nor do I know with the Samsung).