Difference between memorandum report and business report?

Academic writing usually starts with a general description and history of the subject, details of any part of the subject which need to be resolved and an explanation of the current and future situation. It's purpose is more to inform and educate rather than to persuade.

Business writing has to be persuasive. It often will use only the facts which support its own argument, omitting or downplaying negative factors. It will often use misdirection, supplying too much irrelevant information to deflect attention from known problems.