As Iluvbags stated earlier, I have both and I love both. They are similar, but not enough to make me not want to have either one. The Duomo is much more structured than the Speedy. It's also smaller on the inside than the Speedy. With the Speedy, I feel as though I can throw it around and pretty much use it as my everday go to bag. The Duomo, I treat better. It has the gold feet on the bottom and is a bit "classier" meaning now that I have my Speedy, I won't wear it with jeans/sweats like I used to. Although I haven't used my Duomo since I got my Speedy doesn't mean I love Duomo any less...life has just been bummier, lol.
Here's some pics of the 2 together:...