Feedback is giving users an obvious indication that something has happened (most of the time, as a result of a user’s action), is happening, or could happen. Feedback and help should both be:
Depicting interface changes (i.e. feedback) and providing help should not disrupt the user's current process.
Feedback and help should be placed and shown in a consistent manner throughout the entire project.
Use your user's language and mental model.
This communication is essential so that users are not left guessing. If something goes wrong, the interface has to alert the user, and provide instructions on how to correct it. This is where help comes in. These two essentially share the same purpose, and therefore, the same guiding principles.