A subcontractor is added as a "named insured" rather than only as an "additional insured" on the prime contractor's builder's risk policy. Practically, the named insured status differs because the named insured:

Explanation

A named insured is a party to the policy in its own right: it can present a claim, it receives notices and cancellation, it owes the duty to cooperate, and it is on the hook for premium — which is why a subcontractor usually pays for the privilege through the contract price. An additional insured has derivative cover instead, limited to liability arising out of the named insured's work and subject to that policy's terms. None of the other three describes either status. (b) inverts the whole point of being insured. (c) is what an ordinary third-party claimant is, and precisely what a named insured is not. (d) invents a percentage-of-completion cut-off that builder's risk forms do not use; those policies end on occupancy, acceptance, or a stated expiry date, whichever the form specifies.