What is the difference between variation order and site instruction?

A variation order is a change in the scope of work or contract terms agreed upon by both parties, usually leading to an adjustment in cost or time. A site instruction is a directive given by the client or contractor to change how work is carried out on site, but it may not always result in a contractual change or adjustment. Essentially, a variation order impacts the contract, while a site instruction affects how work is executed on site.