hid

ok now i no this is a very stupid question, but is a 9003 bulb the same as a h4? i am pretty sure they are, but i just want to make sure. iv been looking for a hid conversion for my 99 tacoma, but they all say h4. so im just checking. dose anyone know what the best conversion is? what should i stay away from to not burn up my wiring. i no that there was some kind of bulb that burned up the wiring harness. thanks for any help.