Well, it kind of depends on what problems are being triggered, doesn't it?

I have some kind of psychosomatic vasovagal response which is triggered by discussion of blood-related medical problems (or something like that; I haven't pinpointed the exact trigger). It feels pretty typical for a vasovagal response: overall malaise, queasiness, feeling both weirdly hot and weirdly cold, reduced cognitive ability, some weird vision fuzziness, and if I don't take measures to prevent it, potential fainting.

But a vasovagal response feels pretty different than a PTSD flashback, I'm guessing.

I've had things trigger strong negative emotions due (I guess) to my personal history. Feels the same as those emotions ever feel.

"Trigger" in psychology lingo means the same thing it does in regular English: to initiate, actuate, or set off. Like, triggering an alarm is going to have a different result than triggering a TV to turn on.