In the Project Excution ,what is the important , PPE or Safety rules ?

Of course both,you cannot just wear PPE without following safety rules it is non-sense.

As compared to both safety rules is more important

Wearing of PPE is under company Safety Rules. Safety Rules is like a 3D movie theater wherein wearing of 3D glasses is a must and PPE is the 3D glasses.

In the project excution important PPEs are those which is going to be used according the job requirment and the rules are those which is set up by the clien in there health and safety policy.