Is there a logical reason to use one instead of the other? Is there a difference between them? Are they equally interchangeable?
Some possible distinctions that came to mind include:
The distance from where we are now. i.e. one could imply it is mentioned soon, and one would imply it is mentioned much later on.
Perhaps they are different languages, one hebrew and one aramaic.
Perhaps the time period in which the Sefer was written determines which word is used.