Someone earlier in this thread noted that Sophie, Duchess of Wessex was wearing a Canadian poppy and wondered about that. I can only guess that it was perhaps received as a gift on the couple's Jubilee visit to Canada and had special meaning in that way.
But as an American it made me wonder what the heck the difference between the poppies was. Let me know if I have made any errors.
Officially (and yes there are variations, based on who makes them) from the vets agencies of the various counties, here is the style of the poppy:
Britain - two petals, black center and oak leaf
Canada - Four petals (often though, all one piece), black center (and for a while earlier a green center)
New Zealand - two petals, flat, black center
AU - Four petals, black center
RSL in AU, BTW has a great poppy logo -with silhouette veterans placed as stamens in the poppy.
http://www.givenow.com.au/images/org/o00743-1.png
Here in the US - poppies are usually made of red crepe paper. I remember making them as an art project one year at school. We wear them on our Memorial Day, May 31, though I got a lot of LIKES on FB when I added a poppy to my avatar on FB over the weekend.