What is the difference between Aktionsart and Aspect. Anyhow, I'll give it a try. Defined as tense alone, aorist, for instance would be seen as a simple past.
Greek tenses depict more than time.
This concept is often diagrammed on a time line with action depicted by dots, lines, repeated dots, or a combination of dots and lines. Aspect takes into account time and type of action as elements in a verb. It may indeed indicate a punctiliar action in the past time or a linear or repeated action culminated in the past. Perhaps Greek writers employed the aorist to represent action occuring in the present. This has been a matter of great debate in B-Greek.