Akkun and Yukki became gods in both anime and series but in a different way.
In the series, Akkun and Yuno are already dating but they lost their memories after waking up from a coma but in the anime, Yukki and Yuno only met once during an exam, they barely talk, and they were classmates.
The main protagonists in the anime are only kids, I think they were at middle school, while n the series, the protagonist are currently in college.
I don't remember a scene in the anime that they let the timer ran out when the dead end appeared but in the series, nothing really happened when they let the time ran out.
In the anime, when the DEAD END appeared in the diary, a player can change his/her fate by just doing something odd or something that he/she thinks that can change the future but in the series, they can only change their fate by killing another player/destroying the phone and the timer will stop.
In the anime, the player disappeared in a vortex kind of disappearing way when he/she was killed OR when the phone was destroyed while in the series, the player disappeared in a pixelated kind of techie way but only if the phone is destroyed.
This is purely a romantic-science fiction themed series, and for me, not a heck of a thriller which I like the most about the anime.
To sum it all up, again, the story differs a lot from the original, hence, Another World.
The future diaries are only available in Olympia, not in the real world unlike in the anime series which ultimately caused a huge damage including a lot of killings.
There is only one type of diary in the series and it's mainly a phone diary and needs to be a new Chronus Seed Ltd brand of phone but in the anime, there are several types of diaries like, phone, notebooks, blogs, servers, etc.
She is also sweet all the way unlike in the anime where it's like she has a bipolar personality. This time, she really just wants to protect Akkun.
Yuno is not that harsh of a fighter or killer in the series unlike in the anime.
The series didn't include many characters from the manga/anime as well.
Characters' names also differ, a lot, but some names still remained, like Yuno and Deus.
In the anime, Deus Ex Machina is the god of time and space with a power to control everything about it but in the series, Deus is a woman who is the AI (Artificial Intelligence) controlling Olympia, a world for all the patients who is suffering in a coma.
In the anime version, there are 12 future diary owners who fought very damn hard to be the winner and replace Deus Ex Machina as the god of time and space but in this series, there are only 7 diary owners.
Differences between the anime/manga and the series: