The All Star Young Pro Series (CM1100BT) features a padded wrist guard that comes attached while the All Star Young Pro Series (CM1010BT) does not.
The All Star Young Pro Series (CM1010BT) Youth Catcher's Mitt has a lot lower leather quality than the All Star Pro Series Catcher's Mitts. This Youth Catcher's Mitt features the extra soft oil-softened leather shell giving the glove a fast break-in process.
Yes, I think this All Star Young Pro Series (CM1010BT Youth Catcher's Mitt) will fit your player's hand well. We usually suggest a glove with 32.00" circumference length for a regular 13 year old hand. Therefore, I think this 31.50" model will be a good fit considering his smaller hand size. In addition, the adjustable wrist strap will allow your son to adjust that wrist strap to his liking.