Change is situational. Transition is psychological.
The two terms are often used interchangeably, but when you’re going through major (or even minor) life events, it’s important to think about them separately.
Change is tangible: the actual activity/behavior/event that is ending and beginning, such as actually changing jobs.
Transition is intangible: the process of adjusting from one state to another, such as working to break old habits of the job you left while learning the culture of the new job you took.
Transition is harder to grasp, and more difficult to deal with. Change just happens, but wrapping your head around it and adapting takes work. Focus your energies on coping with the work of transition and it will be a smoother ride.