Why do turntables sound different?

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.

Also, some tables apparently sound 'bigger' than others. Some sound 'bigger but slower', others 'bigger and not slower'. This observation does not come from my experience, I read about it.
I would say that my Spacedeck definitely does not sound 'small' and it is not 'slow' at all. Does it have to do with the platter mass and bearing?