noob question, what makes the headset a gaming headset?

i have a cheapo sonic gear headset, with small ear muff and mic.
it serves me well as my friends or game teammates can hear me clearly.
i don't like those ppl using the laptop's built-in mic >.<

the big headphone type (the ones that covers your whole ear) i cannot tahan cuz it'll make me feel nauseous after wearing it for about 15 minutes.