In this video Adam explains Garmin VNAV on the GTN vs the G3X as well as the V-CALC that is on the 2" Navigators.

0:00 Intro
0:12 VNAV Explained
1:31 GTN VNAV
2:28 G3X VNAV
3:00 V-CALC Mention
3:23 GTN VNAV Demo with Multiple Waypoints
7:43 G3X VNAV Demo Single Waypoint
11:36 Few More Things About VNAV
12:27 V-CALC Explained
13:46 Wrap Up