to be pedantic we should probably also use the term "screens count" - the KObo readres, with kepubs, and the Kobo android app dynamically calculate "pages" which are now equivalent to screens, on a chapter by chapter bases , based on your current font, margin, justify etc settings. tweak any of those & the "page" count will change.
but like the man just said - "pages" in ADE speak are constant- an ADE "page" may span 3 1/2 e-reader screens on your preferred device+ settings, but it's a set amount of bytes, and it will display the same in ADE on PC, or on your device. thus if you know you are at page 137 of a side loaded book, you can go straight to that in any other ADE software.
to do that with word count you need a way of quickly getting to word 13,749 or whatever when you change device but want to pickup where you left off in the same book - I suggest that is tricky