htmlB button class...?

Hi, I'm studying htmlb buttons and I'm wondering why there is a difference between:

<b><hbj:button id="button" text="Go"/></b>

and

<b><input type="button" class="urBtnStd" value="Go"></b>

I checked the source of the iView that had the htmlB button, and saw that it used the urBtnStd class, so I used it using regular html. However, for some reason it doesn't look quite the same. I'm curious to see if there a way to make them identical?

Thanks so much,

Baggett.