KHHill91: Does rolling a Ranger or Fighter and changing later do the same thing? (EDIT: same thing as rolling a priest and changing when the stats change) I am pretty new at the game, as I picked it up two days ago.
Not quite.
A character's level is used in most combat calculations, so a character who never changed class will be of higher level and thus get an advantage (or less penalty) against enemies. Especially against enemy spells can a few levels in difference be noticeable.
But a character that changed class will have higher skills (and higher magic skills means access to higher level spells) due to getting those extra skill points when leveling in his second class.
Another thing to consider is that a character's mana regenration is based on his starting class, so characters starting as Priest, Mage, Bishop, Alchemist or Psychic will always have an advantage in that regard.