Difference Between L4D 1 & 2

Aside from the plot difference, there are a few more things that differ from the two games (and they all make the second one sound even better).  First off, the groups of characters are different.  L4D 1 has Francis, Zoey, Louis, and Bill & L4D 2 has Nick, Rochelle, Coach, and Ellis.  Next, the second one has five levels (that intertwine), rather than 4 storylines that don't connect at all.  Their game modes both contain a Versus, Survival, and Campain mode, but the second game also has a Scavenge and Realism mode on top of the other three.  The second game also has a total of ten different melee weapons to choose from throughout the game (which is probably my favorite addition).  Also, the second one adds in ten new different types guns & special ammo/gun accessories.  In addition to the health pack and pills, L4D 2 includes an adrenaline injector and a defibrillator.  Also, instead of just having the normal group of infected, the second installment has three different types of infected: Zombie Clown (Dark Carnival), Hazmat Zombie (The Parish), & Mud Men (Swamp Fever).  On top of the five special zombies (Tank, Boomer, Smoker, Hunter, Witch), there are three more in L4D 2 - Charger, Spitter, Jockey.  Also, the Witches can now travel in daylight.