Set Lerp Start Location

I understood everything but when I set “get actor location” to “lerp a” and player pawn location to “lerp b” crystal following but it lingering to player pawn for a noticeable moment than it destroys.

What causing this to happen?
As lerp a, assigning the location of crystal actor than player pawn location is easier than setting the actor location before timeline. Don’t they same? What is the difference?

I completed this course as well as other ones but as long as I don’t understand everything, it is no difference with copy and pasting. I won’t make same mistake again. I listen more carefully, experiment every possibility almost anything what I can think of. Thus, I need to learn why we needed to set crystal location before the timeline.