A general induction to an organisation may give a basic overview but site inductions can give site specific emergency contacts, specific procedures for working at just that site, policies for that specific site and safety rules and hazards they need to be aware of that are only in relation to the site they are working at.
Keep a record of which site inductions a contractor, employee or visitor has completed. Which sites have they been inducted for? Display a list of site inductions on their induction card or have different site specific induction cards that can be scanned at each site for a compliance check.