Copyright infringement and plagiarism are two different, but related, actions. Understanding the difference between the two and how they can affect your work can be incredibly useful.
To begin with, the definitions for Plagiarism and Copyright Infringement have clear differences:
Plagiarism
The action or practice of taking someone else's work, idea, etc., and passing it off as one's own; literary theft.
Copyright Infringement
When a copyrighted work is reproduced, distributed, performed, publicly displayed, or made into a derivative work without the legal permission of the copyright owner.