What is a variation?
A variation changes the works through the mechanism in the contract. Its effect on scope, cost and completion should be reviewed and documented.
What is a claim?
A claim is a request for a contractual entitlement, such as additional payment or time. A changed activity does not by itself prove entitlement.
Why records matter
Maintain instructions, correspondence, progress records, measurements and cost evidence. Link the event to its effect and the relevant contractual basis.
Follow the agreed procedure
Notice requirements, deadlines, authority and substantiation vary by contract and amendments. Check the actual wording rather than assuming a universal rule.
Questions to take into your project
Practical habit: keep a change register with the instruction, owner, date, scope impact, cost impact and decision status.
Further reading
An introductory overview. Project decisions depend on the agreed contract, facility conditions and applicable requirements.