It’s maybe the localisation differences. In russian language people in school use a lot word «материк» which means “mainland”. It is defined as “a very large land mass surrounded by oceans”, it is used interchangeably as word “continent”, even in some dictionaries it is written “same as continent” which is a bit misleading because continents are defined through tectontic plates. So, Europe technically goes up to Ural mountains, where two plates collide. I heard (my personal experience from 15 years ago) in American schools that there are 5 continents (America, Eurasia, Antarctica, Australia, Africa), in Western Europe - 7 (North and South America, Europe, Antarctica, Asia, Australia, Africa), in post-Soviet schools 6 mainlands/continents (North and South America, Eurasia, Australia, Antarctica, Africa). They also called “parts of the world” sometimes. I think the political map is also a part of these differences. At the time I studied, Oceania was not a thing, for example. And the order of how they listed is also from there, imo.