Okay, I feel stupid asking this, as Ive been in game development for a few years but i need something clarified. I looked in a game manuel(final fantasy 7 I believe) and it said "scenario wirter: Kazushige Nojima". Now I assume scenario writer means they write the story but not the dialogue(script). Am I right? If so who writes the dialogue spoken by the characters? I also saw something called a "text planner", do they write the dialogue? I was also watching the final fantasy versus 13 trailer and it said "base story: Tetsuya Nomura", what does that throw into the mix? Thanks for your answers in advance, sorry for the noob question.

Every company creates different credit titles depending on what that project's needs were.
The only folks who can tell you what "scenario writer" means in this particular case, definitively, would be the writers, designers, and producer of that game.

In Japan, the word "planner" is used instead of "designer."
In Japan, the word "designer" means "artist."

For Final Fantasy VII, Kazushige Nojima was credited as ストーリー・イベントプランナー in Japanese. These three words are basically "story event planner" as a Japanese person would pronounce the English words (approx: sutoorii ibento pulannaa). Though, IIRC, he also did work on the music and did have a hand in at least some of the dialog.