What's the difference between internal and contractual deliverables?

Internal deliverables are visible only to employees of your organization. You can activate them irrespective of the contract status. Use them to track schedules and commitments, internal to your organization. They aren't printed with the contract terms.

Contractual deliverables are contract terms deliverables that track commitments that must be fulfilled as part of the contract. All the parties to contract (External and Internal) can see these deliverables. External party to the contract can edit only those deliverables they're responsible for. Contractual deliverables are listed in the printed contract terms. These deliverables are automatically activated when the contract becomes active. You can't manually activate contractual deliverables. Activation creates deliverable instances that you can manage using the Manage Deliverables task.