Sites works differ from earthworks in the site works are designed to interact with the environment, but earthworks:

Earthworks "merge with their environment".
'Site works' portrays the work required on your building site to set it up for your home to be worked, and also the continuous administration of the building site. 
The earth works refers to the second part of site works which is the work that should be done on the building site to guarantee that your home can be constructed appropriately, that it's worked in the perfect place, and that it will be steady and secure.

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