Is this your first time playing RO?
The full version has all the files you need to play RaijeRO.
(if you are prompted for a password, leave it blank and click OK)

RaijeRO-full_2010-02-23.rar

Do you already have RO installed (Ragnarok and Sakray)?
The lite version has the additional RaijeRO files you need to play.

RaijeRO-lite_2010-02-12.exe