Mobile Phone images being different sizes despite the code having them the same size?

Im trying to place 2 images on my screen, but theyre both set at the same size but ones still appearing bigger than the other only by a little bit but its noticeable to annoy people.

Heres my code

GUI.Button (new Rect (Screen.width/3.50f, Screen.height/2.75f, Screen.width/4.50f,Screen.height/4.50f),"",SlingshotTwig);

And

GUI.Button (new Rect (Screen.width/33.95f, Screen.height/2.75f, Screen.width/4.50f,Screen.height/4.50f),"",BrokenWoodenPole);

See as they are both 4.50f, Slingshot Twig is still appearing as a smaller image - they are both the same image size image.

Sorry if this is hard to understand :confused:

Please and Thankyou in advance

Anyone at all?