The XS1B and the XS2 are physically the same size. But the XS2 is heavier mostly due to the electric starter and larger battery. The XS2 also has a hydraulic front brake, different front fender, and different front forks. That could create an optical illusion of different size.
It could be that the ride height of the front forks has been altered, giving a different size appearance.
Of course, pictures of the two bikes would help...