Under Section 19(8), what is the difference between a 'counter-claim' and a 'set-off' in DRT proceedings?

Section 19(8) allows the defendant to set up a counter-claim against the applicant's claim for any right or claim in respect of a cause of action accruing to the defendant against the applicant - either before or after the filing of the application but before the defendant delivers his defence - whether such counter-claim is in the nature of a claim for damages or not. In contrast, Section 19(6) restricts set-off to an 'ascertained sum of money legally recoverable' by the defendant. A counter-claim is thus broader - it can include unliquidated claims and claims for damages. Under Section 19(9), a counter-claim has the same effect as a cross-suit enabling the Tribunal to pass a final order on both the original claim and the counter-claim.