what is the difference between premium and limited suburb outback

In prior generations it was just about leather, dual auto-climate, and a moonroof. Then the moonroof became a la carte in the 2010-2014 era. But it's more complicated in 2015-2019.... The Premium uses 17" wheels with too-tall 65-series truck tires which severely reduce handling feel. The Limited uses proper 18" wheels with decent 60-series tires. (Yet BOTH benefit greatly from swapping in Subaru's own Sti 20mm rear stabilizer bar...but that's another story.) The Limited gets rear AC and rear heated seats and Harman audio. Note that NAV, Eyesight and Remote Auto-Start are still a la carte. The TOURING model adds everything, but only if you like the chocolate-brown leather.