These 2 concepts are closely related but also different. Change fitness refers to a person’s psychological fitness to meet the demands of the change process. You can think of it like physical fitness. You need physical fitness to run a marathon, but having such fitness doesn’t mean you will be ready to run a marathon next week. You may not be convinced it is worth all the effort, or you may have other arrangements.
But, if you’re not fit to run the marathon you can’t be ready to win it. You might be ready to start, but you’re not ready to finish.
In organisations, things are a little more complex. Organisations consist of people, and each person has a degree of change fitness. When people come together in teams, they pool their change fitness resources, and these contribute to the organisation’s change readiness.
However, organisations consist of more than people. There are other aspects of organisational change readiness, like leadership practices, and communications, and culture.