GS is a touring king in its own. 
With this bike you will get good set of stock features. Like good diskbrake and alloys which are even better than the one offered in GS150 SE.
Much better headlight than GS.
Much comfortable seat than GS.
Gear indicator, Fuel Gauge. Dry Battery
Side taapa locks are there.
Rear drum brake is also better. I had to find a good khradia to get it working properly in my GS.
In the morning when engaging gear in cold engine, it doesn't jerk like GS (problem especially noticeable in winter).
You get the idea. Apart from features, it's a product with better finish and quality.
And then there comes the difference in ride.