The terms Life Insurance and Life Assurance are often used interchangeably and depending on the context mean the same thing. However, there are subtle differences between the two terms.
Life Insurance usually refers to fixed term insurance, where you are no longer protected by the policy at the end of the term. It is insurance because payout is subject to the death happening during the term of the policy.
Life Assurance usually refers to a policy with no end date, also known as a Whole of Life policy. It is assurance because the policy pays out on death, which is assured to happen.