Norwegian to English Science Mathematics & Statistics

Context: writing a master's theses - use of diagrams/figures.
It simply lists "stolpediagram - søylediagram - histogram".
When I tried to find out the difference (if one indeed existed) between "stolpediagram" and "søylediagram", I ended up more confused than ever..
Norwegian Wikipedia gives a definition here: http://no.wikipedia.org/wiki/Søylediagram, but in other contexts these two terms seem to apply to the same thing. And from what I have been able to deduce, "bar chart" is - strictly speaking - a diagram showing horizontal bars, the vertical equivalent being "column charts".

What it boils down to for my context is what is the generally understood difference by Norwegians between "stolpediagram" and "søylediagram"?
I have a nasty feeling that this question is going to lead to even more definitions but here goes....