The full version has 24 pages of the beach photo shoot, where the mini version has only 8 pages (28 actual photos of ayu in the full version, 17 in the mini version).
After that is a two-page photo collage that's the same in both versions.
The large version, here, has a "Legend of Ayu" CD release timeline, very nicely formatted and including cover art pictures. The mini version saves this data for near the end, and it's text-only & not so prettied up.
The large version then includes data on Ayu's major Vivi appearances up until the PoraPora Nikki (Polaroid Diary) feature began in 2001. This includes small reproductions of each page of the articles. For every year after this, as the Deji Deji entries begin for each year, there's another "Legend of Ayu" timeline of releases & Vivi covers. The mini version doesn't have these "Legend" timelines, it just jumps straight into the entries.
The formatting for the entries is different between the books. Some of the photos are bigger in the mini version but for the most part (especially with earlier entries) they've squished more onto each page so everything is smaller. Obviously, as has already been noted here, there are 20 more Deji Deji entries in the smaller book.
After all the Deji Deji entries end, there's an A TALK interview in both. (The interview is preceded by another beach shot of Ayu in the large version, but not in the mini version.) Then, in the large version, there's "A Words," which is a very pretty & nicely formatted section made up of quotes by Ayu, taken from past ViVi interviews. In a HUGE win, the mini version instead has EVERY VIVI ARTICLE REPRINTED. Which is amazing. Every long interview & feature Vivi has had on Ayu is in there.
There are three total "Naked Talk" photos at the end of the mini version, all from a part of the photo session (with her on a couch) that, if I remember correctly, wasn't featured in the November '10 "Naked Talk" issue of Vivi. It's not really as big a benefit to getting the smaller book as the combination of more entries, price, and the Vivi article reprintings are, IMHO. But still, they ARE new photos even if you have Vivi.
Comparison photos:
http://imgur.com/a/dTVmF#0