A spool will have a more aggressive feel exiting the corner. It's also a bit harder to drive vs a ball diff.

Nobody really runs a ball diff anywhere in a touring car any more. They've been eclipsed by gear diffs instead, which use different weight oils to give different characteristics. Currently, im using dual gear diffs in my xray t4. Rear has 500cst and front has 2.5million

I feel like the exit is smoother with a gear diff with very thick oil up front, as well as having increased entry steering.