What's the Difference between standard grade and Commercial Grade Bar Stools??

The main difference is the base of standard grade stools have 1 3/8" thick legs and commercial grade have 1 3/4" thick legs.  Also in the turned leg stools the supports are also turned on the commercial grade bar stools and smooth supports on the standard grade stools. View:

Standard Grade                                                HD Commercial grade

On stools w/o backs (as shown) the wood seat on the standard grade is 1" thick x 12.5"

On the Commercial grade the wood seat is 1 3/4" thick x 14" diameter.

Low back and high back stools come with memory swivels in the commercial grade.

The Low Back, High Back and Cushioned seats are the same on either base.