BETA reader VS ARC reader
Beta Reader: Will receive the book BEFORE it has been edited or gone through proof reading. It is the final draft prior to a new set of eyes, and it may be messy. A Beta Reader gives feedback with regard to content edits, detailed feedback and general feedback. Is not considered a proofreader, but if they wish to note typos or grammatical errors, there is no objection
Arc Reader: Readers a pre-released novel or novella for posting reviews on Amazon and Goodreads