The Bosch GTS 10 J is a portable jobsite saw that is very similar to the Bosch GTS 10 XC. The main difference is that the GTS 10J is slightly smaller and lighter, making it easier to transport to a jobsite.
Besides being slightly smaller and lighter, the GTS 10 J also lacks the sliding table found on the GTS 10 XC. It just has a mitre slot instead, that however doesn’t seem to fit standard custom mitre gauges, so you’re stuck with the one that comes with the saw.
For people who don’t need the portability of this saw, Bosch’s new GTS 635-216 table saw might be more interesting, especially considering it costs about 50% less.
Because it is often used onsite, the GTS 10 J is often sold as a package deal with a foldable stand. There are two different stands sold by Bosch, one with normal legs (GTA 600) and one that also has two wheels attached (GTA 60 W).
There used to be some extension rails available (as seen in this video), but these seem to be no longer available. You may find them on the second-hand market.