Acknowledgment letters are actually letters of receipt. They are formal and short letters, mainly serving legal purposes. In business, such letter plays an important role as it indicates that you value the opinion and time of the concerned party. Writing such formal business letters can help you to build goodwill and trust.
Announce letter A letter of the announcement is a letter that announces a special event or occasion that people need to be aware of. It could be for a special sale, a concert, or even a birthday party. Letters of the announcement are usually informal, and state in clear, concise terms what the event is and what further action should be taken by the recipient.