Beta-reading involves reading your unpublished novel to see how a reader will perceive it as is. A good beta reader will offer constructive critiques, suggest edits, and help the writer in identifying issues in flow.
Proofreading is essentially making sure there is nothing technically wrong with you book. Grammar and spelling are important here, but no ideation or structural help is offered.
Editing can range in price and can be as simple as line editing, to structural reformatting, to entire chapter rewrites. A developmental edit can help with transitional issues, too.
Every book needs to be edited before being published. Writers are great at finding the diamond, but editors are needed to polish it to perfection.
Trying to edit yourself is just patting yourself on the back. You feel better, but you didn’t really accomplish much.