Too Long; Didn't Read
The purpose of copywriting is to sell, while the purpose of content writing is to educate or inform. Content writing is more about educating or informing the reader than copywriting. Copywriting goals are typically short-term, and you're expected to generate real sales from it within days and weeks. The tone of voice you use will be different for each type of writing. The key is to know when to use different styles of writing for different purposes. The time frame for creating results is how you measure success.