I realize it's been a while since your post, but since I just joined the forum I thought I'd still respond.
Th biggest different is the DCT has a split palm/shell, which is laced together. This gives you the snugger fit of a smaller glove and the long extension of a big glove with added control. It's a brilliant design that was introduced in the early '60's. The DCT pattern is the oldest baseball glove/mitt pattern still in current production.
The FM19 pattern has a slightly wider break, with extra lacing in the middle of it.