Downgrade or Downdate...?

LOL, sorry for my stupid question but i realy wanna know if there is any diference from Downgrading and Downdating...
if i want to change my PSP firmware of 2.6 to 1.5 i should look for a downgrader or a downdater.....
thnx a lot and sorry about my question!

Just download this file via this link http://www.psp-hacks.com/file/605 , and just follow the easy instructions when you launch the program.

Don't restart your PSP when it tells you to no matter what though! It will tell you to reset your PSP when it is finished downgrading, but there is no visual aspect to the downgrade, so it is just guesswork. But your PSP WILL restart on it's own if you let it be. I guess some people on the QJ forums bricked their PSP's because they didn't know when it was finished downgrading because all you can see is the flashing memory stick light. SO PLEASE DON'T RESTART YOUR PSP WHEN IT IS FINISHED BECAUSE IT WILL ON IT'S OWN!!! Sorry for the urgency but a bricked PSP is just so sad.

You can un brick a psp you know.

If you have 1.5 and use a custom firmware you can unbrick it, not if you are downgrading. You can't unbrick a PSP missing it's major PRX's either, but there isn't really anything out there that accesses them. So if you downgrade while it is overwriting your major PRX's, then like everyone else with a brick, you can have a nice $250 coaster or a paper weight.

Come to think of it I do need a new coaster...