HTML ITEMS input top != text top?

Hi,
is there anybody who can please explain me what is the difference between
 the top Position of an Input box and the top Position of a text?
The Code below paints a spare, an Input box and a text box on the Screen.
Input box and text box are on the same top value but look like the picure below.
<img src='background.png' style='; left:0; top:0; width:800; height:480'/><a href='http://domain.com'><input type='text' value='0.0' style='font-family:Tahoma; font-size:38; text-align:TopRight; font-weight:Regular; ; left:0px; top:15px; width:250px; height:55px'></a><p style='font-family:Tahoma; font-size:38; text-align:TopLeft; font-weight:Regular; background-color: rgb(255,128,0); ; left:250px; top:15px; width:150px; height:55px'>text<p>

Thanks in advance,

de-kekse