assure vs. ensure or insure

All of these have the general meaning of the root “to make sure,” but their use is somewhat different.

Assure is to promise or say with confidence. It is more about saying than doing: I assure you that you’ll be warm enough.

Ensure is to do or have what is necessary for success, to make sure something will happen, or to confirm that this is the case: These blankets ensure that you’ll be warm enough.

Insure is to cover with an insurance policy. I will insure my home with additional fire and flood policies.