I just got my Sweetie Blue USA version yesterday and noticed the card differences with the body and eye colors. I also noticed the name tags on the sparkle ponies are plain on the international cards, but "fun" on the USA ones. "Special Edition" is also added to the USA ones.
Also, the pamphlets are different. The ponies are rearranged differently on both sides. I haven't taken a close enough look, but I wouldn't be surprised if the ponies on the USA one have adjusted color schemes.