Why do turntables sound different?

Bearings...interesting.  I'm actually considering a bearing upgrade on my SL-1210.  I have a choice of two bearing designs:

* optical grade Sapphire-Ceramic bearing from The Funk Firm

* The Timestep bearing has the spindle as a solid single piece of polished 303 Stainless Steel with a much larger base diameter and the bearing is polished PB102 Phosphor Bronze. A silicon nitride ball and PTFE thrust pad are fitted. The whole assembly is in a captive oil bath so that you can use more suitable thin oil, or any oil of your choice.

Any recommendations?

Without knowing more about it the sapphire/ceramic design should have far less drag.  

Thank you for your thoughts.  I will go that direction then.

There is one table that sounds different from ALL others---the various incarnations of the Townshend Audio Rock. It is the only one ever made to feature damping at the front/cartridge end of the arm, rather than at it’s rear/bearing end. Though now almost impossible to find, Townshend offered it’s damping "trough" separately, to add to any table/arm.

I venture to suggest that quiet bearings are more important than low friction bearings. The two may not be the same. Although air bearings do seem to be best in both respects.

Also important is the resonance of the platter, especially in designs which do not use air bearings.

Just two of the considerations which affected my DIY.