Agreements are generally signed with the contractor when the duration of the contract is long and there are chances that many things may change(eg taxes, duties, prices etc ) during the execution of the contract. In order to take care that such disputes do not arise and a legal remedy is always available to both the parties, agreements are signed. However, signing of an agreement may take time because it is to be legally vetted in detail ensuring that all the terms and conditions of the original tender, post-tender closing clarifications, conditions, price negotiations etc etc are exactly incoporated in the agreement. This may take one or two months
In order to start the work immediately, a Work-order is generally issued by the client to the contractor so that the contractor can mobilise, order material etc. The terms and conditions of the Work-order are the same as that of agreement, however, any mistake, omissions etc detected in the Work-order can be corrected at agreement stage.