Stepped insurance premiums increase with the age of the insured.  Level premiums stay the same until the insured reaches age 65.
 
Advantages:
 
a.  Level premium policies will probably be affordable to age 65, at which time they may revert to Stepped premiums.
 
Disadvantages:
 
b.  Stepped premiums increase each year, and may become unaffordable.  This may cause the insured to drop the policy due to cost when they are likely to need it the most.

c.  Level premiums are more expensive in the beginning.