What is the difference between two construction Company One Use Completed Contract method & Other Use % Of Completed method?

The completed-contract method of accounting is used by manufacturers and contractors.  Unlike the percentage-of-completion method, which attempts to recognize revenues and gross profit in the applicable periods of construction, and not soley in the period when the construction has been completed, under the completed-contract method of accounting, revenue, expenses, and gross profit is deferred until the completion of the contract.  If at the end of the business fiscal year of a company work on a contract remains incomplete, no revenue, expenses, and profit on that contract is recognized in the current year on the income statement; all costs and billings are accumulated in respective balance sheet accounts.

In completed contract method revenue is recognised only upon completion of construction. Recognition of revenue is deffered until completion. Under percentage completion method revenue is recognised in proportion to the expenditure incurred or contract completed.

In completed contract method the company took whole item of work and expected the completion of the full package like full building  and the payment for the execution is paid by the client on different terms according to the contract agreement , but for the  percentage completion it is awarded part of the job partially and payment is effected up on completion of that part based on the contract agreement  ( partial relative to the whole project)  eg. finishing work of the building