The Walking Dead began as a faithful adaptation of the comic book series but soon went in a completely different direction thanks to budget restrictions, fan input and the logistics of creating realistic zombie hordes.
One way in which the show differs greatly from the comic is the cast of characters, and many of the most popular figures in the comic aren't featured on the show and vice versa.
Most people know the Dixon Brothers Daryl and Merle aren't even in the comics, but many of the other significant differences between the comic and TV versions will surprise you.
I don't want to give away any spoilers, but if you enjoy the TV show and/or comic and don't care about spoilers you should check out this Ranker list of The Greatest Walking Dead TV Vs Comics Differences.
It's interesting to see the differences spelled out in such a clear cut way, but it will straight up spoil some major character events.
And if you're on the fence about all things The Walking Dead I would suggest reading the comic book series before (or instead of) watching the show, because in my opinion it really is much more enjoyable overall.