Which is better.. cool mist humidifiers or warm vaporizer? whats the difference?

i have them both.. the cool mist is wired tho. i cant see it coming out ... its Just a lillte fan in the front. idk if its the brand or that is how the all are.. the vicks vaporizer i see the steam.. but i dont know if i have to put anything in it?can some one please help..my baby is very congested:)thanks