An interim COO is different from a fractional one. Interim means full-time but temporary: someone steps into the seat every day to cover an absence, steady a business through change, or bridge to a permanent hire. Fractional means part-time and ongoing: a few days a month, indefinitely.
The two solve different problems. If you need a pair of senior hands in the building every day for a defined stretch, that is interim. If you need senior operational leadership on a lighter, continuous basis, that is fractional.
Getting this distinction right matters, because hiring for the wrong model wastes money and attracts the wrong kind of help.