Is the Yosemite File Vault password (usually) the same as login password? So when I upgraded to Yosemite, I can remember turning on FileVault. I cannot remember the password I used. Is that password is the same as my login password for my administrator account (the only account on the computer)?

I'm nervous that I will one day have to remember that password, and if it isn't the one I'm already using, I might be in trouble. I've searched around for the answer, but I'm not finding anything. I might just not be describing the correct dialogue box.
OS X will usually attempt to sync the password if you change it, but it's possible to have them different. I have them differently right now, so that my old user password is required at the pre-boot screen, but once OS X is booted, I need to log in again with my new password.

See more info in this answer: How can I have one password for FileValue 2 (pre-boot password) and another for my user login?