Assure
Part of speech: verb
Definition: To make sure and secure. To give (someone) confidence in the trustworthiness of (something). To guarantee, promise (to do something). To reassure.
Example sentence: I'll assure you this: I will have nothing to do with politics.
Insure
Part of speech: verb
Definition: To provide for compensation if some specified risk occurs. Often agreed by policy (contract) to offer financial compensation in case of an accident, theft or other undesirable event.To deal in such contracts; subscribe to a policy of insuranceTo make sure or certain of; guarantee.To give confidence in the trustworthiness of.