what factors are responsible for differently displaying webpages in different browsers?

hi guys!
i designed a webpage with <divs>.Now if i open the same webpage in IE8 it looks exactly how i designed/want it but the same code if i open it using FF it looks way out of my design.
pls help me how to learn and fix that problem.what are the factors behind it.
thanks

Thanks for the information

hi sanjay
thanks for reply
http://validator.w3.org/check
upload ur html file here to validate the code and learn how to find ur small mistakes u made in writing the code.
thanks again sanjay

Hi Vishnu
Could you tell little bit more clearly where you got the problem in using the div tag.
If you could navigate through the previous discussion topics in the css discussion board, you could view some of the questions related to it, possibly that could help you. You could get lot of solutions by just googling the topic.
Please mention the exact problem.
Regards,
Sanjay S Nair