Operating model, sourcing model and contract model
Three choices almost always presented as one.
How the organisation internally allocates decision-making, accountability and capacity. An internal choice.
Who delivers: internally, per service, bundled or integrated. A market choice.
How the agreement is structured legally and financially: input, output, outcome, open book, performance incentives.
The difference in one sentence
Operating model decides who decides; sourcing model decides who delivers; contract model decides how it's settled.
A contract can transfer execution. It cannot outsource the client role.
Why they get conflated
Providers sell all three in one proposition. 'We do IFM' describes a sourcing form, implies a contract form and silently assumes an operating model on the client side.
Why it matters
Taking a sourcing decision without changing the operating model leaves an organisation unable to steer what it has bought.
How to tell them apart
Ask three questions separately: who decides, who delivers, and how is it settled. If one answer dictates the other two, the concepts have collapsed.