Assure Ensure I Make Strong Definite Happen Early

Both assure and ensure mean "to make (something) certain" but assure also means "to tell someone in a very strong and definite way that something will happen or that something is true."

When you want to say that something makes (something else) certain, use either assure or ensure.

• Leaving early will assure/ensure a prompt arrival. [=leaving early will make a prompt arrival certain]
• You can assure/ensure the safety of your home with a security system.
• I will assure/ensure that the package arrives on time.

When you want to tell someone in a strong way that something will happen or is true, use assure.

• He assured us that we would not be late. [=he told us in a definite way that we would not be late]
• The company assured the family that their house was secure.
• I assure you the package will arrive on time.

I hope this helps.