What is the difference between an insurance provider and an insurance plan?

As the terms are commonly used, an insurance provider is the is the insurer itself (that is, the risk-bearing entity). In contrast, an insurance plan is the program of benefits available to participants, which is usually reduced to writing. Sometimes, especially in the case of managed care arrangements, it is itself referred to as an insurance plan. An example would be a health maintenance organization (HMO),

This illustrates one of the prime reasons that it is vital for you determine the identity of the entity that is financially responsible for paying claims.

As the term us usually used, an insurance provider is the insurer itself, meaning the risk-bearing entity. In contrast, the insurance plan is usually interpreted as being the written document that sets forth the terms of the insurance.

That said, sometimes the term "insurance plan" is used in the context of managed care arrangements like HMOs. An HMO is a risk bearing entity that provides a mileau of services to its members in return for a monthly payment, usually called a "contribution" (rather than a premium).

It is critical that you know the identity of the entity that has the financial responsibility for paying claims and ensure that that entity is duly licensed by the insurance regulator of the jurisdiction where it issues your contract/policy.