What is the difference between a levain and a starter

I'm getting sort of confused about this.  I used a packet of French Lalavaine "starter" from KAF to make a whole bunch of levain, made some bread and gave about 4 cups of it to a friend.  I have about 4 cups left sitting in my refrigerator waiting to be turned into bread this coming weekend.  Can this be considered a starter?  It's got a nice tang, gets bubbly and expands when warm and I would like to keep it going because the bread tastes so good. 

I also have some of the Carl's 1847 Sourdough starter working too, it didn't start off as being very tangy, but I gave it about 2 tbs of rye flour and it took off and has a very lovely tang to it.  This is something I recognize as starter, but I'm not so sure about the levain mixture.  I'm drying out a bunch of the levain to use like the KAF recipe did (1/4 tsp levain to 3/4 cup water and 2 cups flour) - my "mad scientist" experiments continue, but I would appreciate some advice or even a good scolding if I deserve it!! :)