I hope this is sarcasm.

CoD - arcade FPS with fast TTK and a variety of different guns, terribly balanced and populated by the people right below terrorists on the tier of awfulness. Medium numbers of people in game. Battlefield - authentic FPS with a slower, but still fast TTK. Balanced. Variety of weapons. Largest number of people in game. Authentic games and arcade games are VERY different by nature. Authentic ones work on the making the game more real without compromising on the fun and making it into a sim. Arcade... Well arcade is basically CoD. Halo - slowest TTK (overshields), normalized weapon set (each weapon is its own type, lesser weapons overall). Low number of people in game. Titanfall - arcade FPS with free running mechanics and mecha, middle of the line TTK and normalized weapon set. Middle number of players in a game. Destiny - slower TTK, has mechanics like double jump, supers, and whatnot, has a variety of weapons of each type. Lowest number of players in a game. Each game has some similar characteristics, but each one is distinct and could not be confused with each other. Things like whether there are weapon types (with several weapons within each type) exist and how many players are in it and what the mechanics besides guns are make a huge difference. In addition, these all (besides CoD and BF some of the time) take place in different contexts. No sarcasm. Just common sense and experience with (unfortunately, in CoD's case) all of the games.

I feel you. CoD is nothing like other shooters, if anything though, other shooters follow CoD too much.

This. Battlefield is leagues ahead as a fps