I absolutely love the Stella McCartney fragrances.  There are quite a few different ones that are available or have been available (but hey, with eBay even limited edition stuff is still available, right).  Here is a break down of the fragrances from my perspective:

Stella Rose Absolute: features the rose more prominently, just a deeeper fragrance (I have heard it described as between Stella, and the pure perfume) more concentrated than Stella.

Stella Sheer: is actually a LE made in different years and as far as I can tell from the previous research I have done is actually a different perfume for each of the years. This is NOT well known. According to basenotes.net Stella Sheer 2005 notes are: Iced Lemon, Green Apple, Celestial Rose, Precious Amber. Sheer Stella 2004 notes are: Rosewater, Green Tangerine, Bulgarian Rose, Alpine Roses, Amber, Dades Rose. From Nordstrom.com Stella Sheer 2006: "The new Sheer Stella offers a fresh and sparkling interpretation of Stella for a summer seduction. First, the delicacy of the Bulgarian rose shivers under the freshness of the lemon and the granny apple. At heart, the feminine and sexy rose absolute combines with the celestian rose transparency for a subtle gentleness. At last, the amber brings the unmistakable mystery and sensuality of this frozen eau de toilette. " I am unsure if it was also reformulated this time or if the LE bottle was the only change.

Stella Sheer 2007 from sephora.com the notes are "Lemon, Green Apple, Celestial Rose, Amber." The Stella Sheer is much lighter than the original, very summery, but I love the original.

Stella EDP: Rose, Peony Flower, Mandarin, Rose Absolute, Amber. I find that this really lasts all day on me and in a really nice way. I actually find myself wearing this more than the pure perfume.

This original Stella comes in many forms including the four piece roll on set, a special spray travel size with refills, and different sized bottles as well.

Stella Pure Parfum:  This is beautiful as well, but I find myself wearing the EDP more than the pure stuff.  It doesn't have as much sillage and is also kind of a pain to open the bottle and dab.  It is pretty, but I only use it rarely.