From my experience, an abstract is concentrated information gleaned from a white paper that is used on an external source.
Examples of an abstract would be:
In each example (and several others) the abstract appears outside of the actual framework of the white paper document.
In comparison, a summary is where concentrated information gleaned from a white paper that is used internally within the referenced white paper.
Examples of a white paper summary would be:
In each example the summary appears inside of the actual framework of the white paper document.
The problem occurs when the two terms are used in the place of each other. When the label "abstract" is used instead of a "summary" and vice-versa, reader confusion is sure to follow.
Now I'm sure the world isn't going to end if you happen to label your executive summary as an abstract, but if you produce several white papers as part of your business marketing plan, consistency becomes an important element that retains reader interest and keeps them coming back for more.
With that said, most business readers are used to the term "summary" to reference a concentrated information section of a white paper.
So why swim against the tide and risk greater reader confusion?