What is the difference between Health Insurance & Critical Illness policies or Critical Illness Riders in insurance?

A Health Insurance policy is a reimbursement of the medical expenses.

Critical illness insurance is a benefit policy. Under a benefit policy upon the occurrence of an event, the insurance company pays the policyholder a lump sum amount. Under a Critical Illness policy, if the insured is diagnosed with any critical illness as specified in the policy.

The insurance company will pay the policyholder a lump sum. Whether the client spends the amount received on the medical treatment or not depends on the client's own discretion.