I was going through this lecture, where Leonard Susskind explains that these two Feynman diagrams are considered to be equivalent in QFT:
One diagram explains the same phenomena in one possible way and the other describes the same thing in a different way. But, when I look at it, it seems an awful lot that if you take one of the diagrams, and rotate the entire space by $90$ degrees, then you get the second diagram.
I know that one of the axis represents time, so it is not as easy as I described, but imagine drawing one of these on a paper and then rotating the whole paper.
So, of course rotating the entire co-ordinate system is a coordinate transformation, but I don't know whether any coordinate transformations apply in QFT.
So, my question is, are these two situations equivalent i.e. if I make a $90$ degree rotation of the coordinate system, is the same as the second possible process for the phenomena? And if they are similar, would this mean that you would have to count the second possibility in the path integral, as it is the same first possibility turned over?