Correct, the novel thing Element X does different is sliding sync which allows for much faster partial syncs when the app is opened. The classic apps would have

Correct, the novel thing Element X does different is sliding sync which allows for much faster partial syncs when the app is opened. The classic apps would have to do a much more substantial (and energy intensive) sync each time it was brought up to foreground. The big drawback are the X versions are still very far from feature complete.