A deductible is the amount one has to pay before insurance starts paying. After the deductible is met, you may have to pay a small percentage of the cost until you reach what is called the "out of pocket max", whereupon the insurance company pays everything.
I have a policy called a Preferred Provider Organization, or PPO. The insurance company signs up doctors and facilities who agree to prices far below the artificially inflated prices they charge someone with no insurance - discounts of 75-90%. The doctors do this because they have access to a large number of customers and are assured payment without having to chase non-payers all over the place. This is a big deal for them because a lot of people outside of these networks never pay their bill.
In the past I have had a Health Maintenance Organization, or HMO. In these, the company pays pretty much everything from the start and you never see a bill. The drawback is that you are usually severely restricted as to the doctors you can see. Oh, and they cost more.
Understanding coverage is difficult, even after 30+ years of being insured. It's always changing, with new nomenclature to learn.