Crop+letterbox , same resolution and not (any kind) of resize.. right?

[Bartoloni]

i was pretty sure this is how works  CROP and LETTERBOX... for example remove top/bottom noise of a VHS and make final output as the same resolution of original... right?

i placed 2 clips (one cropped+letterbox and one not) side to side and using my eyes seems there are not differences ... i'm correct?
there is no resizes involed if i use letterbox to reach the same resolution of original clip...

i 'm a lot worried about losing details.. just this. (talking again about PAL 720x576)