Mortgage Life Assurance is designed to pay off the remaining mortgage debt on repayment mortgages if you die within a set period. It ensures your dependants need not worry about repaying the mortgage if you die.
The name says it all. It's term assurance, as you only get a payout within the set 'term' e.g. 18 years. Its level, because the payout you get is fixed from the start of the term until the end. Level term assurance thus guarantees a known lump sum payout upon death within a fixed time e.g. £150,000 if you die within the next 18 years.
Although Critical Illness cover is sold by life assurers, there is a big difference when compared with life insurance - you don't have to die to benefit from the Critical Illness insurance policy. This type of cover is designed to pay out a lump sum in the event of you suffering from certain types of critical illness or if you have to undergo certain types of surgery as specified in the policy terms and conditions.