If you are too lazy/cheap to read the comics, but want to know how they differ from the TV series, this should help fill in the gaps. I will try to pass over the more trivial things. For instance, in the comics, Rick puts on a pair of jeans and a t-shirt before leaving the hospital, but in the show, he travels to his house in his hospital gown. This information is neither important nor interesting, so who cares?

1. In the TV show, Rick is from a small town in Georgia, but in the comics, he is from a small town in Kentucky.

2. In the comics, we never see Shane visit Rick in the hospital; the little girl Rick shoots in the beginning of episode one doesn't exist in the comics.

3. The TV show delays Rick's first encounter with zombies a bit - in the comics, he finds a barred door (but it doesn't have "Don't Open - Dead Inside" written on it), opens it, and finds a cafeteria full of walkers.

4. Morgan's zombie wife is not in the comic books. Rick never gives Morgan a radio in the comics; he does however give him a police car.

6. In the comics, when Rick enters Atlanta, he does see a tank, but neither he nor anyone else ever crawls under/hides inside of it. After being pulled from his horse, he just runs, and is suddenly grabbed and pulled into an alley by Glenn. He also never drops his bag of guns.

7. After Glenn rescues Rick in the comics, they do not meet up with other survivors inside the city. They just run/sneak past the walkers, and run back to the camp, which is where Rick finds his family and where he first meets everyone (except Glenn, who he met in the city, and Shane, Lori and Carl, who he already knew). The campsite is also MUCH closer to the city - only a few hundred yards away - so they escape on foot.

8. In the comic books, Shane never tells Lori that Rick is dead. He just helps her and Carl get out of the city; on the road, and in a moment of desperation and weakness, Lori sleeps with Shane once and immediately regrets it. In the TV show, it seems to be an ongoing relationship.

9. There are a number of people on the TV show who do not exist in the comics: Merle, Daryl, Jacqui, Morales and his family, and all the people in the campsite who never had speaking roles and were killed in the zombie attack. There is a large, black former-football player named Tyreese in the comics, but no "T-Dawg". I assume they are in fact the same person.

10. Carol is in the comics, but she is not married to Ed, she is a single mom. There is a character a little like Ed, but his name is Allen and he has 2 twin sons, and a wife named Donna. He is not an abusive husband or father.

11. In the comics, because Rick didn't drop the guns and Merle doesn't exist, Rick never leads a second group of people into the city. On one occasion, Glenn leads Rick to a gunstore where they become trapped and it is then that they smear themselves with zombie guts and sneak around them. Again, the campsite is close enough to the city for them to escape on foot.

12. Because no second group goes back for Merle or the bag of guns, they never meet the Vatos or visit a nursing home. In fact, they don't meet any other survivors until they reach Herschel's farm.

13. In the comics, shortly after they meet, Dale warns Rick that a) no one likes or trusts Shane, and b) Shane is in love with Lori.

14. In the comics, Rick and Shane get into an arguement about whether they should leave the campsite. Shane punches Rick in the face. Shortly afterwards, Rick and Shane are alone in the woods and Shane pulls a gun out and prepares to kill Rick. Carl (who is already carrying a gun at all times) has secretly been following them, and he shoots Shane through the throat, killing him almost instantly. Only after Shane is dead do the others decide to leave camp.

15. Absolutely NOTHING from the final episode of season 1 ("TS-19") happens in the comics. This episode is the largest deviation from the original story so far, except maybe for Merle/Daryl being there. The characters on the TV show already know FAR more about the disease and its effect on the rest of the world than the comic book characters do. Actually, there has never been any mention of other countries in the comics, and no one has been able to tell them anything about what the disease is, how it started, what it does, etc. No one has tried to reach the CDC.

16. In the comics, the survivors quickly begin calling the walkers "zombies", and admit it seemed silly to say that word at first, but soon felt more natural. Frank Darabont, Robert Kirkman, etc have made it clear that this will not happen in the TV series. In the universe of the TV show, the word "zombies" doesn't exist, and neither do the movies of George Romero.

 

Season 2 Update:

In the first 2 episodes of the second season, I picked up the following changes.

1) The herd thing doesn't happen in the books, and Sophia never goes missing. T-Dawg/Tyreese is never injured.

2) Between the camp and the farm, the survivors find a walled community, move in, and are chased out by lots of zombies.

3) Otis shoots Carl because he thinks he is a zombie, not because he can't see him. The bullet hits him in the back and lodges in his shoulderblade, so the injury is nothing life-threatening, and Shane doesn't need to go on a suicide mission (which is fortunate, because he is already dead).

4) Dale and Andrea are an item already by this point in the comics; since the CDC thing never happened, they have nothing to fight about and Andrea was never suicidal.

4) Herschel has MANY children, most of whom are still alive when the survivors find the farm.

 

Oh, and in the comics, they have already gotten through the first summer/fall, then most of the winter, and it is late winter/early spring when they find the farm.

 

I think he says he's from Georgia at some point, and in any case, a walkie talkie on the outskirts of Atlanta isn't going to be able to reach into Kentucky or any other state. He is from Georgia.

 

I forget where, but at one point he says he's from King's County, Georgia. His truck has Georgia plates, and so did his squad car. He also told Morgan not to come to Atlanta as soon as he got his walkie talkie back. And he was still a long way from the city when they heard him on the radio - he hadn't run out of gas or found the horse yet.

 

Indeed it has begun.