These two are conflated because both keep operations moving, but they work at different altitudes — and confusing them leads to hiring the wrong solution for the problem in front of you. An operations manager executes within the operating model: running the day-to-day, hitting targets, managing a function or team well. A fractional COO designs the operating model itself — the ownership, cadence, quality and governance that the managers then run inside. One operates the machine. The other builds the machine worth operating. They are not competing roles; they are different jobs, and a healthy company past a certain size usually needs both.
The distinction that matters is between execution and design. When an operations manager is struggling, it is often not a performance problem at all — it is that they are being asked to run a model that was never properly built, or that has stopped scaling. No amount of capable execution fixes a structural flaw in how decisions, quality and flow are designed; that is a level above the manager's remit, and asking them to fix it is asking the wrong altitude. Equally, when the model is sound and the gap is simply capacity to run it, a fractional COO is overkill — what you need is a strong manager, not an executive to redesign something that already works.
I am clear with prospective clients about which they need, because the two are genuinely not substitutes and the cost of getting it wrong runs in both directions. Hire a manager to solve a structural problem and the structure stays broken while a good operator burns out against it. Bring in a fractional COO when the model already works and you have simply spent executive money on a management gap. Where I add value is the structural case — when how the business runs needs designing or rebuilding — after which your managers run a far better machine than they could before.