Bkay,
FMQing in the ditch is usually harder because you need to manage both to stay in the ditch & to keep stitch length consistent.
The 80/20 is noticeably higher loft than W&N (which isn't 100% cotton, but something like 87% cotton & 13% synthetic scrim). It's not an enormous difference, but it is visible. The bonding process is also different, requiring a quilting distance of no more than 5" to preserve the batt (which I would argue is still too far apart for a child's utility quilt).