What is the difference between letter, memo, e-mail, texting and formal writing?

Memo is also called a memorandum which is a concise and informal communication within an organization to inform about policies, procedures, or any other official message.

Letter is a form of written communication addressed outside the organization. It contains a long formal message to inform someone of a specific topic. The tone of the letter depends on the relationship between sender and recipient.

Email is another form of routine electronic communication within an organization or outside the organization. It requires an email account and internet connection.

Differences

The major differences between Memo, letters, and Emails are as follows −

Memo	Letter	Email
Short and Precise	Long and informative	Informal and routine message.
A signature is not required.	Duly signed by the sender.	A signature is used as a complimentary closing of the message, which is automatically inserted.
It is exchanged within the organization.	It is exchanged between the company and the client.	It can be exchanged between anyone.
It contains a header, date, and subject.	It does not contain any header. Formal language is used to convey information to a specific person.	It contains an introduction, body, a closing, subject line, and recipient's email id.

The differences between texting and formal writing are as follows −

Texting simply provides the information whereas formal writing not only provides information but also provides the context and sub context of the information. For example, if we have to report sales figures by texting, we will simply write the data but when we formally write it, we will explain everything related to sales figures.
Texting is an informal way of sending messages across the person whom we intend to send it to. But formal writing is the formal way of informing the reader about the information.
Formal writing is more descriptive in nature whereas texting has simple intimation features. With the help of a text, we intimate the reader about the subject. Whereas, with the help of formal writing, we can give a detailed picture of the subject.