As far as what an actual tactical light is.... Look at the real thing, an original SureFire 6P. Add features that don't remotely get in the way of its ultra simple User-Interface. Such as an LED. A pocket-carry clip (either bezel-up or bezel-down). A narrower head for EDC purposes. Increased output. Along with a beam that is geared for a good combination of both flood and throw. (Perhaps favoring flood a bit more.)
Any add-on extra simply eliminates a light from being the real thing. From experience: Extra buttons or switches, FAR too easy to accidentally hit under stress. Whether a tailcap + side-switch combo., or two switches on the tailcap. And if you're using Turbo, what's the very next mode after if you accidentally hit that mode-selection switch? That's right, Low. Not good. Literally the only exception to this.... Thrunite TT20. The moment you activate that tailcap switch, the side-switch becomes disabled. Stays that way until the light is switched off. Brilliant! But, all is not perfect with the TT20 (though if you want the equivalent of an Olight 3S without the magnetic charging feature, this light is the closest you're going to get).
Momentary-only tailcap switch. Best for a true tactical light. Good luck finding that outside of SureFire, and a couple of Streamlight models. So, properly-made forward-clicky switch. Easier said than done. Above mentioned TT20 switch is nearly hard as a rock to push.
Ears on the tailcap: Great for preventing accidental activation of your light. Literally never had an issue with that. Gives you a lanyard attachment point. Worthless feature on a real tactical light. Let's you tailstand the light! Great, on an EDC light. Worthless on a true tactical light. Plus, those ears get in the way when you need to grab your hand-held tactical light in a hurry and activate it. Seems like a minor thing. Until you're hitting the range on a regular basis to train/practice with your concealed carry pistol. Sometimes when you draw your light from a pocket or holster, you over rotate it in hand. You go to slam the pad of your thumb onto the tailcap switch, and instead slam it onto one of the metal ears. See how long that nonsense lasts before you switch to a light without those silly ears on it. Sadly the TT20 has ears.
If you have a full tailcap shroud with a soft-press forward-clicky switch that isn't proud of the shroud, but level with it; you get the tailstanding feature but without the horrible disadvantage of ears.
More than one switch, lower modes that aren't hidden away, and a set of ears; call it what you like but that's not an actual tactical light.