Here's my interpretation on health insurance, However, I am by no means an expert on this.
Deductible - what you have to pay out-of-pocket before insurance kicks in, usually applies to prescriptions, non-standard procedures (i.e. not a doctor's visit).
Copayment - fee you pay at all doctor's offices, hospitals, wellness centers, etc. before you get to see a doctor (the reason this exists is to prevent people from thinking all medical services are free, you might not go to the doctor for a cold if you have to pay $30. Keeps costs down).
Coinsurance - percentage you have to pay up to an out of pocket maximum for certain services. Let's say you have your pancreas removed. It costs $20,000. Your out of pocket maximum is $3,000. You pay $3,000 for that surgery.
Let's say you have 80% coinsurance (where the insurance company pays 80% up to your out of pocket maximum and then covers 100% above that amount). Same surgery as above costs $10,000. I believe you then owe $1,000 for the deductible, and then 20% of the remaining cost or $1,800 with a total bill of $2,800. I may be wrong on this part, though.
I believe there is also a prescription drug benefit that pays 80% of the costs for non-generics once your deductible has been met. I believe with some plans generic drugs are like $10. It just depends on the plan and insurance.