Power Grid China/Korea strategy - is it any different from the base game?
At a high level the strategy is the same.  Obviously the difference in connection costs between cities and the different resource refresh rates will create strategic differences, but this is fairly complex and nuanced and so beyond the scope of an answer.

As far as the rules differences, the changes to what you want to do are more tactical (what you do this move) than strategic (how you plan the game).  The more strategic changes are as follows:

For Korea, you don't want to combine coal and nuclear as the North has no nukes (ironic) but has the cheaper coal.  Garbage plants are also more competitive on Korea, so take that into account when planning your power plant build.

For China, since the power plants come out in order, there aren't going to be windfall opportunities (a plant that powers 5 cities won't be available until you get to that part of the deck).  Here, you pretty much want to upgrade your plants only when you need to get more capacity rather than opportunistically (when there is a plant that looks good), as there is always going to be a better plant coming up next.