Different Layout for 4" and 5" phones

Im pretty new at developing android applications and i want to have to different layouts for 4" phone and 5" phone. Ive tried using layout-sw320dp for 4" phone(Nexus S) and layout-sw480dp for the 5" phone(Nexus 5).

However the layout gets cramped up while using the nexus S. Ive tried using layout-small and layout-normal. Didnt help.

Thanks Sahil