Is my encryption password the same than Apple?

When you made your first encrypted backup you were prompted to enter a password - twice. However, that could have been years ago; you are only prompted the first time you made an encrypted backup, you will never be prompted again until you go to restore a backup.

When you entered the backup password if you have a Mac and have Keychain enabled you were given the option of saving the password in Keychain (this is the default). So check Keychain for it.

If you haven’t erased the phone yet you can create a new backup with a new password—>About encrypted backups on your iPhone, iPad, or iPod touch - Apple Support

If neither of those work you get unlimited guesses, so try to guess what password you might have entered back when. If you are like most people it will be a password that you reused. And to speed up the process click to change the password and you will be prompted immediately.

You should ask yourself that, because you have create both passwords yourself.

Read again -> Related Article -> About encrypted backups on your iPhone, iPad, or iPod touch

👉 When asked, make a password. Create one that you'll remember or write it down and store it safely, because there's no way to use your backup without this password. If you forgot your password, learn what to do.

It could be, but it is not by default. When you encrypt an iTunes or finder backup, you are prompted the first time for a password. You make it up and enter it, so it is whatever you typed in.

If you use a Mac you would also have been prompted to save the password in your Keychain, so you could check for it there.

Not necessarily, no.

It is whatever you set it as... If you don't remember it, then you can't restore any backups encrypted using that password.