This form of Frieza has long black horns that stick out from his head.  His head is lide some kind of helmet it serves for no purpose, mainly beacuse he doesn't really fight in this form.  Frieza uses this form to hold in all his power.  He tricks his enemies or enemy by showing off this form.  His power isn't that great at this stage.  And this is Frieza's smallest for.

 

Frieza Form 2:

Form 2 shown Frieza with the long black horns the curve upward on his head.  He is the tallest in this form and has shoulder protection that becomes wider.  His tail is longer and pind.  In this form, Frieza brings out a more power.  His speed and his strenght increase.  This form he also has a bigger neck, more muscle mass, and a way deeper voice.

 

Frieza Form 3:

In this form, Frieza is his ugliest.  His head is stretched out to the back and he has two white horns on each side of his head.  They curve just a bit and a longer.  His shoulder protection sticks out more in this form, but they still have purple on them, just like head.  His strenght increses when he is fighting Piccalo, and his speed also.  But he only stays in this form for one  episode and changes after Gohan's outburst of power with the mesenko ki blast that he deflected.

 

Frieza Form 4:

This is Frieza's last and final form for him, his brother Cooler achieves a higher level than his Frieza.  he has no pink on him in this stage and his shoulders don't have shields.  In this form Frieza becomes shorter and his face changes.  His ki and his strenght increase 10 fold.  And he can change his power by percent, when Goku was using 50% of his power Frieza was only using 1%.  He can go up to 100% power which is his maximum.  His shoulders bulge when he increases his percentage in power, but his speed increases other than decreses with the new found strenght from the muscle mass.