Two policies can look identical and settle differently
Replacement cost pays what it takes to rebuild. Actual cash value pays that figure minus depreciation for the age and condition of the building. On a twenty-five year old rental that deduction can be very large, and the two policies can carry the same dwelling limit while producing completely different checks.
The cheaper quote is frequently the depreciated one
Where a landlord policy is noticeably cheaper than another, the settlement basis is one of the first places to look. It is not a trick, it is a different product, and it is worth comparing on that term rather than on premium alone.
Roof surfaces often have their own basis
Even on a replacement cost policy, the roof can be endorsed to settle at actual cash value once it passes a certain age. On a rental you are not inspecting monthly, that endorsement decides the outcome of the most likely large claim.