Copyright infringement is when you take someone else's creative work, copy it, and share it with others without their permission. You are interrupting the revenue stream of the original creator and, even if credit is given to the original creator, if they did not give permission to use their work, it's infringement and it's against the law. It can be completely accidental. You are still liable to the same consequences however, whether it is done purposely or not, so be careful. If there is ever a question, ask the library.
Plagiarism does not have to be done maliciously. It can be completely accidental. You are, however, still liable to the same consequences whether it is done purposely or not, so be careful. If there is ever a question, ask the library.