Different file/DVD sizes when using different apps

I just recently began (again) looking into backing up my wife’s DVD collection. My research has led me to rip w/ Fab5 (free main movie to HDD) then burn w/ImgBurn. But I have done more testing this weekend of DVDFab and ImgBurn along with Nero, DVDShrink3.2 and AnyDVD w/CloneDVD. What I have come across when ripping my original movie DVD, depending on the app, the same files often come out in different sizes, same issue happens after burning.
Ripping the entire movie to HDD it came out in different sizes using Fab5, Fab4 and CloneDVD (that may have something to do with DVDFab’s error correcting)
From the original movie I ripped the main movie to HDD with Fab5 was 4.042,731,520. Burning w/ImgBurn came out with 4,043,333,632; CloneDVD came out with 4,043,300,864 (this was the same size as buring straight w/Fab4 registered version).
I assume different encoding? Does this size difference really matter when all the movies actually appear to play ok. Fab5 and CloneDVD movie only came out the same, so I’ll probably stick with one of these. I quess my question is, will these minor size difference cause prblms in my copied DVD’s when I play them? I don’t want to have to watch the entire copy everytime I make one to make sure it’s ok, no skipping, freezing, etc…

Question 2 I can illustrate. When ripping an original movie I noticed some of the files on that movie (especially the big files that are of different sizes) become different sizes on the bkup/copy. Here’s a few of the files in question, most likely the main movie files.

ORIGINAL:
VTS_01_0.VOB 47,662KB
VTS_01_1.VOB 1,048,524KB
VTS_01_2.VOB 1,048,042KB
VTS_01_3.VOB 1,048,300KB
VTS_01_4.VOB 1,048,516KB
VTS_01_5.VOB 229,774KB

DVDFab5 rip to HDD:
VTS_01_0.VOB 47,662KB
VTS_01_1.VOB 1,048,574KB
VTS_01_2.VOB 1,048,574KB
VTS_01_3.VOB 1,048,574KB
VTS_01_4.VOB 1,048,574KB
VTS_01_5.VOB 228,874KB

Any help or comments appreciated?

Prolly the way the tools remove bogues sector information from copyright protection schemes makes a difference here.