BELOW IS THE LIST OF ANSWERS TO YOUR QUESTIONS:
Question 1: Are you sure one of the rasters is actually a DTM?
Answer 1: Yes sir, I have generated DSM and DTM both as a result of drone2map i.e. by processing of drone images.
Question 2: What is the cell-size of the DSM, DTM and the Difference rasters?
Answer 2: Attached below is the image which shows cell size of DSM as (0.02421, 0.02421), DTM as (0.12104, 0.12104) and the difference raster as (0.12104, 0.12104).

Question 3: Also could you provide the Min-Max values of DSM and DTM raster?
Answer 3 : DSM (Min. = -10.7023 and Max = 64.5238)
DTM (Min. = -10.6558 and Max = 48.2257)
The minimum and maximum values can also be confirmed as per the screenshot below:

Question 4: It looks like you have sorted the records in ascending order of the Z-value. What values do you see when you sort it in descending order?
Answer 4: Attached below is the image which shows values sorted in descending order of Z value.
