如果……就…… "如果" indicates if and follows one or more conditions that cause the result follows "就". Often we'll use it to say something not be realized and we feel shame about it. 只要……就…… "只要" indicates restriction and it can only follow one condition which cause the result follows "就". Often we use it to say something we are quite sure about. e.g. 如果有包子就能吃饱了。---Maybe you have other foods to eat but you are still hungry. 只要有包子就能吃饱。 如果你在这就好了。---You were better to be here but you weren't at that time. 只要你在这就好了。---If you are here things'll be better however other conditions change.