I posted this in the ancient times of 2005 and I will post it again now.
Even though I'm not an AGD, I always thought this was rather interesting.....
Alpha Gamma Delta has 2 versions of its crest or "Armorial Bearings"....
The American version:
The Canadian version:
"Alpha Gamma Delta chapters in Canada have a slight variation in the design of the Armorial Bearings. Chapters in Canada use the Coat of Arms without the helmet.
Rulings of the British government do not permit anyone except the sovereign to bear the Royal Helmet".
And since Canada is still part of the British Empire, hence the different crest.