What are some differences and what are some similarities between physician coding and facility coding?

Coding involves assigning a number to a treatment or procedure for the purpose of billing for said service. Since hospital costs are based in a different location, and have different operating and associated costs than a physician office or outpatient clinic, the codes are different. Also, hospital bills are paid from a different portion of most insurance, and frequently have different copays, coverages and allowable costs. Wrong code and you may not get paid at all, or vastly underpaid for the service provided.