The "New" G class (2019+) is completely different in/out. The older is built better and will last longer. But yes 2018 and older w463 exterior is mostly the same other than the front bumpers and grilles that they changed throughout the years.
Just had to replace head gasket in 2002 with 28k Miles. Pretty reliable other than that. Don’t want too much rain or water on sun roof either. Drainage issues