A temporary email is a buffer, not an identity
A fake email address, a disposable address, and a temporary email all point to roughly the same thing: an address you use for a short task, not for a lasting relationship. It gives you a working address that can receive sign-up verification codes, activation links, and one-time messages without tying that traffic to your personal mailbox. The key distinction is that it is real enough to receive mail, but temporary enough that you should not treat it as part of your long-term identity.
It helps to think of temporary email as a buffer between you and the internet. When a site asks for an email address, what it often wants is a way to confirm you are human, complete a registration flow, and keep sending follow-up messages afterward. A temporary email gives that site a working contact point without opening your personal email to every store, forum, download page, lead form, and experimental service you try.