Why do turntables sound different?

There is no formula for audio GESTALT, so science is not going to jump on that band wagon.

Mankind science is a finite observation of infinity.  We can only hope infinity in the long run, will have its day in court.

So for this finite point in time, using our ears, is the best final judge for our own gestalt systems.

Bearing friction plays a large role in a decks subjective sound with higher friction designs often but not always imparting a dark, slow signature.  "Stretchy" rubber belts also are responsible for this type of sound. 

Bearing friction..
Anyone experimented with different oil? I didn't. I just use Nottingham's oil that they make for their tables. The sound is on a warmer slightly darker side and there is nothing slow to it. Belt is like new, doesn't feel or look wrong, only about 600 hours on it.

You were wondering why tables sound different. I mentioned the bearing because it is an often overlooked component that enormously contributes to sound quality. 

The bearing design comes into play , after the design of the table and materials and lower or higher mass are given. Then the appropriate bearing is designed for those criteria and used to suit specific scenario. Look at the mass and close tolerance of a micro seiki bearing , and the lead impregnated lube it utilizes for a massive platter and mass record weight ability. You wouldn't use it to spin a rega platter. Even the lubricant on some tables is chosen to offer more friction with the intention it will help with speed stability (+ - drag). As long as the bearing can carry the load upon it, and do it effortlessly with no chatter/vibration, the motor and the power supply will champion or fail the best of tables. Its not about speed accuracy , your ears are much more agile at spotting fluctuation than a steady slight slow or fast rpm. Where the belt rides in relation to the bearing/spindle point is more critical than some tables / owners realize as well.
It all , still , like it or not boils down to the materials chosen as a whole, the design to implement them and the drive used. No matter how much more is spent for better materials, higher quality of machining parts, tighter tolerances and better power supplies/motors and esoteric materials better suited at rejecting vibrations,
and tone arms ......it still is at the mercy of the home environment and the ability of the end user to make it sound "different". Different in these terms would be to that specific user as being "better" as the reason of personal choice.
However, if that user is not truly skilled at set up of the table, the arm , its placement and the treatment of the room the previous means nothing.

As I said in my prior post before, there are 2 reasons. The biggest reason IMO and IME for "different sound " is the end user him/her self. These days many dealers lack real skill with set up . The designers build tables to cost and sound how they think is best (different) . Different is simply the factors of personal taste for looks and sound as well as individual price points of choice.
You don't need a scientist to tell you if a chunk of aluminum will ring louder and for longer than a slab of panzerholz.