12. Difference Being unsolicited is persuasive in approach with emphasis on You attitude and an appealing format. Usually brief and precise. It is an unsolicited communication sent to customers/suppliers. It is an intra-office communication which seeks to bring to notice important matters of the organization. Letter conveying some information from a businessman or organization to a large number of customers and /or suppliers. A letter or a memorandum addressed to a number of persons or intended for general circulation in the organization. Circular Letter Office Circular