Sentinel 1 data : terrain correction deviation

When I used the POD Precise Orbit data to perform the terrain correction for the Sentinel-1 images, I found that the corrected result always has a few pixel deviations compared to the standard image. However, when I used the SARScape tool in ENVI to perform the terrain correction, there is no deviation between the corrected results and the standard image. Can you tell me what the problem is?

plz help me.
Thanks all…

What do you mean by “standard image”?

High Precision SAR Corrected image

That is not a Sentinel-1 product…how are they generated?