Works contract and construction service

I have a few queries regarding the subject:

(1) Does works contract necessarily mean construction "purely" or does that have only an element of construction activity or both.?

(2) Why is works contract singled out and defined separately u/s 66E(h) of Fin.Act '94.? Does that mean its totally different from "construction".? Bcos construction service is separately defined u/s 66E(b) as a "declared" service.?

Thanks and Regards