Are there any characters in the comics that aren't in the show? o the other way around?

Yup. Darryl is the main addition to the show. Also Hershel had two young twin girls in the graphic novels as well as Maggie. I can't remember if her sister in the mostra is in the graphic novels. I'm sure there are lots of other people but I can't seem to recall since it's been so long since I read the graphic novels. The personalities of some of the characters are certainly different. They've toned down a lot of the craziness in the show.

There are a lot of characters that are in the show, but not in the comics and vice versa.
Some examples:

In the TV mostra but not the Comics:
Jenny, T-Dog, Jacqui, Merle, Daryl, the Morales, the Vatos, Dr. Jenner, Beth, Randall, Jimmy, Dave, Tony, Tomas, Oscar, Big Tiny, Sasha, Donna, Allen, Ben (There are characters named like the three last in the Comics, but it's not the same characters at all), Milton, Karen, Tim, Crowley, , Shumpert, a lot of Woodbury folks, Clara, Ana, Sam, Tara, Lilly, Meghan, Mitch, Pete, Joe's group, Mary, Gareth....

In the Comics but not in the TV Show:
Donna, Allen, Ben, Billy, Julie, Chris, Lacey, Arnold, Susie, Rachel, Shawn, Billy (there are two Billy, both not in the show) (Hershel actually has 7 children in the Comics), Dexter, Thomas, Alice, a lot of The Governor's guys, Gabriel, Heath, Denise, Holly, Jessie, Ron, Gregory, Jesus, Ezekiel, Negan, Dwight.... and much more.... but I haven't caught up in the comics yet, so I don't all know the characters just yet, but there is so many characters in the comics!

I know for sure that Daryl is not in the comics and neither is Sasha... and Lydia from the comics is not in the show, and neither is Negan o lee... :/