Some very good comparison information on here
https://www.revzilla.com/common-tread/2019-bmw-r1250gs-and-gsa-first-ride-motorcycle-review
'
GS versus GSA
There are three main areas of difference between these two bikes that should be a consideration for potential buyers: size, protection, and suspension.
Next to the GSA, the GS looks almost tiny. The GSA is a massively large machine, and a lot of that girth comes from its 7.9-gallon tank. It offers an additional 2.6 gallons of capacity over the base GS’s 5.3-gallon tank. The GSA tips the scale at a whopping 591 pounds, 18 pounds heavier than its predecessor and 42 pounds heavier than the base GS.
BMW R 1250 GS First Ride Review
Compared to the GSA, the standard GS looks almost small by comparison. Photo by Kevin Wing.
Some of that weight comes from the crash protection that’s standard on the GSA. Factoring this in, the weight difference between the two bikes becomes smaller, since most folks who buy a standard GS will still install crash bars.
BMW R 1250 GSA First Ride Review
The main performance difference between the two models is the increase in suspension travel that the GSA receives. Photo by Kevin Wing.
The most important performance-oriented difference between the two bikes is the fact that the GSA gets a longer travel, taller suspension. At the front end, the GSA features 8.3 inches of travel whereas the GS only gets 7.5 inches. At the rear shock, the GSA offers 8.7 inches of travel to the GS’s 7.9 inches. This translates into a standard seat height of 35 to 35.8 inches for the GSA and 33.5 to 34.3 inches for the GS. There’s also a lowered-suspension version of the GS, which gets that bike down to a 31.5-inch seat height. A lowered seat can drop the height even more.
While the GSA felt tall, even to this six-foot, three-inch-tall rider, the truth is it also felt incredibly balanced and stable, even off-road.'