Decreasing term
This is usually the cheapest option, and is designed to cover gradual repayment of debts, such as a mortgage.
Level term
As the name suggests, this is a level of cover that will pay a fixed amount if the policy holder dies within the agreed term.
Increasing term
With increasing term, the payout increases each year in an attempt to mitigate inflation. However, this also means that your premiums may increase each year.
Whole Life
This lasts until you die, regardless of when that might be.