What is the difference between the Rate of change analysis and selecting ‘Rate of change since’ when doing a Scalar analysis?

The Rate of change analysis:

Calculates the changes from the end of each time series while

“Rate of change since” in Scalar analysis:

Calculates it from the end of the whole calendar. Meaning that if some series do not end at the same observation date, the calculation range will differ.

You can set the “Range Start” and “Range End” in the Scalar analysis to make sure the calculation is done on the same range across all input series.