What is Two-Factor Authentication?
Two-factor Authentication (2FA), is a security process in which users provide two different authentication factors to verify themselves. Two-factor Authentication adds an additional layer of security to the authentication process by making it more difficult for attackers to gain access to a person's devices or online accounts because, even if the victim's password is hacked, a password alone is not enough to pass the authentication check.
What is the difference between Google Two-Factor Authentication and Two-Factor Sign-In under the Security page?
The Google Two-Factor Authentication option only provides security protection for functions when required. While Two-Factor Sign In extends the protection to safeguard login security. That means when it's enabled, you will need to enter the Two-Factor Authentication Token to sign in to your account, providing an additional layer of security.