The way I understand "tactical" is not exactly the actual definition of the word, but when applied to firearms and shooting, its kind of like "a feature (a pistol grip) or action (a tactic) that serves to enhance the execution of a direct and imminent action (defensive or offensive)."
So a "tactical" shotgun with tactical features - a pistol grip, extended magazine tube, ghost ring sights, flashlights, speedloaders...etc. - is better equipped to carry out the specific job of self defense or offense against threat elements. Whereas a shotgun without the above tactical features is a wee bit less capable of @$$ the user toward his purpose.
However, as people should know, you can have all the tacticool stuff while being untrained in its employment and fail just as well as if you had a bone stock gun in the same untrained hands.
Personally I hate all the tactical marketing crap. I think its used to sell merchandise for the most part. You have all these xbox heroes with their first person shooter games in god mode and they think they know everything about what it means to be a - tactical "operator". All I can say is try before you buy. These will be cannon fodder if they can ever actually get off the couch - which is unlikely.
That being said, things change over time. I'm more open to tactical "stuff" than I used to be. Some things are useful and effective - like surefires, and some things aren't - like forearm pistol grips. I mean, how are you going to clear your barn of zombies at night without a surefire? :cool2g: