User blog comment:MasterBroccoli/Civilization icons/@comment-27274076-20191110133451/@comment-5157002-20191111181006

It also wasn't as necessary - AoE's DE didn't introduce any new units, buildings, civilizations, or campaigns, just a few redesigned scenarios (and a lot of minor game changes).

AoEII's DE introduces four new civilizations (each with unique technologies and units) and three campaigns, plus some new technologies.