On different websites that allow their visitors to create user accounts or sign in their user accounts, Log In and Login are the words that are frequently used. Both words can be especially confusing to people because they have the same meaning, yet they are different parts of speech. Therefore, they can never be used interchangeably.
Login is a noun or adjective. As a noun, it means a username and password to enter a computer, program, or website. As an adjective, it describes the screen or page in which a person will enter the computer, program, or website
Example: I can’t access my Facebook account because I am not getting the login page. (adjective)
Log in is the verb form, meaning “to enter a computer, program, or website”.
Example: In order to post something on Facebook , you must log in to your account. (verb)