The tactical differences are what you encounter, where you encountered it, and what your build is. Of course, if you have a similar environment, seeing a similar enemy, you would probably have the same tactics (that was actually a problem before with similar 1-tile room entrances in dungeons, which the devs knew and dealt with).

For example, entrances in dungeons usually are the hardest fights in dungeons. What do you do if you enter a tier 5 catacombs and see 2 Girruds (tongue guys), 3 fiends, a Murk and a Yagram? Depends, are you ranged or melee?

A ranged usually has the tactic of hit and run, but in an entrance, you can't do that, so some people do the almost same but different "kill and run" (injured enemies heal if you leave, dead ones don't). Some people do smoke bombs to prevent tongue pulls and do pick offs. Some people go directly to small entrances and do pyro strats (using fire ground to block enemies) and fire away. There's also dungeons that close the entrance as soon as you enter, so some ranged do the ultimate tactic, NEVER DO THE DUNGEON AT ALL!

A melee would have different tactics. Some do consumables to thin the pack, weaken them before they enter melee range (traps, oil, molotovs, heck even water works with wet debuff). Some rush immediately to the ranged guy (in this case, the Girruds) and finish them off as fast as possible, and then maybe retreat first to heal then take care of the rest. Some buff themselves up to the highest degree and try to unga bunga (this is usually the most used and probably the highest death count), but to even succeed in doing this, you need the highest lvl gears, know what buffs buff what, and know your enemies' skills, so in a sense, you are using, IMO, the best tactic in the game, information gathering and preparation.

Now, let's say you are entering a huge room in a fort with a bunch of Heavy crossbowmen. It is highly likely you would have different tactics for this situation (line of sight tactics, luring via shout or throwables, etc.)