I found that the Titium was a lot less padded and really hurt the front of my forehead whereas the Speed Air fits like a glove.
I bought my Titium when I had short hair and it was quite snug. As my hair grew longer, it got more and more painful to put my hair up into it, so I ended up getting a CO for awhile, and then a Speed Air. I went up a size in the Speed Air and it fit great, but I would like to think that this is due to the amount of hair that I had when I bought each rather than a sizing difference.
I had a 58 Titium Pro and got a 59 SpeedAir. The Titium always hurt my forehead, the SpeedAir is generous and completely comfortable. So my guess is they fit about the same and I should have picked up the bigger Titium Pro way back when.