Is DEM data the same as the Elevation Corrections on GC?

Really learning the ins and outs of my Instinct Tactical Solar.  As I read threads about the elevation inaccuracies I started to really play with the settings and calibrations.

I just learned about the elevation corrections on Garmin Connect, and that data seems very accurate compared to my topo maps on Gaia.  When  I calibrate the watch using DEM, the altitude also seems very correct compared to Gaia, not so much if I calibrate using GPS.

I am curious, is the data that DEM pulls when calibrated using DEM, the same data set that appears on Garmin Connect through elevation corrections?  It would make sense, but I can't see that confirmed anywhere.