That's "roughly" it...
The R1 set is 5 dual layer doubles sided discs (in actual fact the extras disc is single layer dual side and one other is dual layer one side single layer the other )
The content is identical on the two sets (barring PAL-NTSC conversion)
here is the specification/content comparison Link Removed
BTW Link Removed is an excellent site for just this sort of question
Don't know I'll let you know when I've watched the R1 (It's only just arrived)...
The R1 release is quite a bit cheaper being around £50 ($76 ish) at some online retailers and prices start around £85 ($130 ish) R2...
R4 maybe a decent compromise as it is PAL and retails slightly above R1 price (around £55 - $84 ish)...
To be honest given the age of the series I don't think a PAL-NTSC conversion is going to ruin it too badly especially as the old footage is sometimes not in great shape anyway.
EDIT - Of course the use of single sided discs makes the R2 release easier to handle and makes it less susceptible to damage... Personally I saved the £35 and plumped for R1 despite living in UK
The archival footage in the R1 World at War set looks terrific for it age and origin! I am sure that it must have been transfered directly from a film source, not video tape, and been cleaned up a bit. The 'making of' documentary at the beginning of the first disk seems to be from a PAL source and the clips from series look bad, fadded/scratched/etc., but don't worry, the episodes themselves are better looking than I have ever seen most of the combat footage look before.
I just recently finished watching the entire 26 episodes of The World At War. (R1)
I thought I knew a lot about WWII until I watched this amazing series. I didn't!
A harrowing, heart wrenching, terrifying
lesson into one of the bloodiest eras in recent memory.
Highly recommended!