"The Walking Dead" is the latest pop culture cult favorite to jump into the adult coloring book craze with the release of its own grownup coloring book. However, there are two different versions out for pre-order at online retail stores. What's the difference between the two "Walking Dead" adult coloring books, and which one will you get?

Grownups went back to coloring in 2015, and the popular pastime hasn't waned. While it has given many artists the opportunity to publish their designs, the trend has also attracted the interest of movies and TV shows. In fact, "Game of Thrones," "Outlander," "Sherlock" and "Harry Potter" adult coloring books went on sale last year.

"The Walking Dead" creator Robert Kirkman and artist Charlie Adlard are releasing the first coloring book in May. The 96-page edition is actually a collection of some of the pages from the original comic book series, which was reprinted for fans to render their own interpretation to some of the goriest drawings.

A second "Walking Dead" adult coloring book has been published by Insight Editions, and it is coming out in September. This 88-pave version is based on the AMC TV show and not the comic series. The drawings have the likeness of the actors playing Rick, Daryl and the other characters, and the settings highlight Alexandria and Woodbury.

Adult coloring books grew popular because they encourage zen habits and mindfulness. "So many things in life are hard, but coloring in a coloring book is easy. It's a nice way to relax," said Michal Ann Strahilevitz, a behavioral economist. The activity also encourages creativity without the pressure of creating art. "We don't have to be any good at drawing to make something pretty," Strahilevitz added.

However, if you're wondering how stress-relieving "The Walking Dead" coloring books are, given its theme and illustrations, it should be noted that these were made for avid fans of the series and not regular coloring hobbyists. For instance, it would be fun to have the coloring books during a "Walking Dead" viewing party, where everyone gets to color their favorite pages first before an episode airs.