- To assure someone is to remove someone’s doubts.
- To ensure something is to make sure it happens—to guarantee it.
- To insure something or someone is to cover it with an insurance policy.
Some sources note that people use assure, ensure, and insure interchangeably. All three verbs have something to do with “making sure” and are therefore similar, but each of them has a distinct meaning that makes it better suited for some uses than the other two.