Agito isn't a "smaller project," it was considered 'equal' with Versus and XIII and Haeresis will be the same. Going by the compilation standards, each game is a jump off point; basically even something like Agito could spawn sequels, manga, merchandise, etc. based on itself.

Canon wise SE said all the games take place in the same universe but in vastly different locations at different time periods. There's probably hundreds or even thousands of years separating them so I wouldn't really expect Lightning to pop up in Versus XIII, but at the same time I would expect to direct references to one another. Nomura and Kitase like to do things like that.

Well go there and you'll see: http://www.finalfantasyxiii.us/wp-content/uploads/2006/05/fabula_nova_crystallis1.jpg As you can see, the circle for agito is smaller than circles for XIII and versus XIII...

Wow tremble you know a lot of stuff I didn't knew yet =p.

Well I'm a huuuuuuge FF fan ^^

they only have in common mythology.

STORY, gameplay and style are difference in 3.

its like FF versus = FF 14 with a sudden change to japanese action RPG

and agito = FF15 .

they are not even directed by the same people all designs are by nomura but he only directs versus.

From my understanding, both Nomura and Kitase wanted to make FFXIII, so by doing this both their visions can be realized.

I beieve the games take place in the same Universe, but other then that their is no connection.

if you have noticed the SE insider event a few months back, on the event's website, Versus XIII was described OFFICIALLY to be 'the core' or 'carry the essence' of the XIII series. Take it what you will as the main game of the "XIII" series.

One thing is sure.
VERSUS WILL HUGE !!!
and xiii will...
will be on 360 :S
I hope sold will HUGE ON PS3 and the 360 version dont afect the ps3 version...
Final Fantasy was exclusive to Sony since long time.