Multiple features of their infotainment are there but softlocked out, the engines on the more powerful trim levels aren't different or tuned, it's just a different ecu map, etc.
I have observed that myself with the infotainment system of my 2017 Golf Alltrack, but when did they start software derating their engines? My understanding is that there's nothing much to be gained from an aftermarket ECU tune unless I switch to premium gas and the more powerful Golf models have other real differences like bigger turbochargers.