To use careen in a sentence, convey the sense of rapid and potentially unsteady movement, often with an element of swiftness and loss of control. It can describe physical objects, like vehicles or boats, or metaphorically apply to people or events rushing headlong in a particular direction.

The word career is used to describe a person's professional or occupational path. It can refer to the entirety of one's working life or a particular profession or sector that an individual works in. Use it when discussing jobs, professions, or long-term professional plans.

To summarize, careen is a verb that denotes uncontrolled, swift movement, often used to describe vehicles or objects in motion, while career is a noun reflecting an individual's professional life or occupation. The distinction between careen and career is clear once you consider their different functional uses: careen is about movement and instability, whereas career relates to work and professional development.