From a traditional marketing standpoint, the answer to the above question is simple.
Content marketing is the creation of valuable content that has a marketing purpose. For example, my company creates an awesome special report, and we exchange it for your email address and your permission to educate you further about our stuff.
Copywriting is designed to get the reader to take a specific action. Sometimes that’s making a purchase, but it can also be confirming an email opt-in, calling for more information, or going into a store to check out the merchandise.