There is a misunderstanding here. It is incorrect to say
runway 36 is north end of the runway
Runway 36 is the entire runway, with traffic moving to the north (i.e. facing about 360 degrees, magnetic). Runway 18 is the same north/south strip of pavement, with traffic moving to the south (i.e. facing about 180 degrees).
If you're lined up ON runway 36, you're at the south end of it, facing north. If you're on final for 36, you're south of the runway, pointing at it -- again, facing north.
If you are taxiing on the airport surface and need to cross that runway somewhere in the middle, it is correct to be cleared to "cross runway 36..." or to "cross runway 18..." or even to "cross runway 18/36...", typically followed by the taxiway you're to use: "... on taxiway Alpha." If there is no direction associated with the use, people typically refer to "Runway 18/36" in order to be clear, although sometimes you'll hear only one designation used. Either way works in that case.
The "Approach End of runway 36" is the end of the runway that you first cross on approach, so the south end. The "Departure End of runway 36" is the end that you cross after having departed on that runway -- so the north end. And, the "departure end of runway 36" is the same end of the same strip of pavement as the "approach end of runway 18". Which description is used depends on context -- i.e. if runway 18 is active (i.e. aircraft are arriving from the north & departing to the south), then controllers are more likely to talk about the approach or departure end of runway 18, than to refer to things in terms of runway 36.
