If you are the type of person who uses the same login details, like the name and password, on multiple platforms, then you are unconsciously using single sign-on or SSO. SSO is a type of session and authentication that allows a user to use similar login credentials across different devices and platforms. SSO can be used by anyone -- an individual, a startup business, an organization, basically anyone who wants an efficient login experience. 

Multi-factor authentication or MFA is a type of authentication process to ensure that the user is the legitimate owner of the account being accessed. Coming from its term, there are various ways to authenticate an account and this may be in the form of questions, phone number or email address verification, or fingerprint scanning. An MFA is used not only to authenticate accounts but also for applications and VPN. 

Keep Your Accounts Apart.