Call of Duty has lots of references to real life war, and the attachments for the weapons are also very realistic, although they have different names. There are also real guns in the game, such as the MP7, RPG and Ballistic Knife. Although Call of Duty doesn't have the same multiplayer teamwork feeling as battlefield, it is fun to work out what you're teammates are doing and trying to help them out.
Call of Duty is as realistic as Battlefield. If you take a look at both games, you will see that there is not much difference between the two. They have similar weapon and graphics, so the only thing that really separates them is the game mode that they come with.
Both Call of Duty and Battlefield are very realistic video games. It is in my opinion that they are both extremely comparable in terms of how realistic they look. If I had to choose one over the other, I would choose Call of Duty as being more realistic of a game overall.
Call of Duty is way more realistic than Battlefield because the guns are awesome and the scopes are like exactly how things are in real life. They even added a dog that can sniff out nearby enemies and assist the players in attacking. The maps have become more interactive now too.
I see Call of Duty as being less realistic, or less authentic, than Battlefield.
The guns don't have as much kick, the weapon camos are too far-fetched for the setting, air or ground support can't just be called in when a team or player is doing good, etc.
However, Battlefield also has its downfalls. You can't revive everyone with defibrillators (especially after falling a huge height), or have orange triangles appear in front of you, or even drive any vehicle you want like a one-man army.
ARMA, as a military simulator, beats both franchises in terms of realism, even if the game itself isn't 100% realistic. I can even say Insurgency is more realistic as well.
Call of Duty isn't as realistic as Battlefield, but the series isn't intended to be ultra-realistic. The CoD franchise focuses upon big set pieces, explosions, and immersive stories. They take some liberties with reality, but they do so on purpose. Battlefield, on the other hand, tries to make itself a realistic war game.
While I am not a Battlefield player, I have seen people play the game, and have seen many videos of the gameplay. To me, both games exercise the same element of realism, while to me the major differences in the games are the gameplay style and exactly what the character can do.
No video game is quite realistic to war, but Battlefield is definitely closer. Call of Duty may be more fun, but you will never see guys camping in a room with enemies running around with knives in real life (infected). And in Battlefield, manning tanks and helicopters, while blowing up buildings and clearing destructive paths is more realistic than Call of Duty's shooting a rocket launcher at a wooden wall and just seeing a black stain from the explosion on the wall.
Isn't it awfully obvious? Call of Duty is not as realistic as the Battlefield series. There are REAL guns in both series, (mostly) real attachments on both, but seriously? One has attempted to be more realistic by adding bullet drop (a real phenomenon), destruction, suppression, etc. The other has prrks (can a soldier choose a focus perk and shoot his targets while getting shot without flinching???) smoke grenades (keep in mind smoke grenades are PHOSPHORUS GRENADES! They burn people and can be poisonous. Not to mention thermal sights cannot see through it since it is HOT) and quickscoping (no person right in his mind would attempt quickscoping)
Either way, BOTH are unrealistic. The game closest to realism available to the public would be Arma, but there are even more realistic games available to only the military.