Question about Editor and Page look

Hello,

I have been working with wordpress for a bit now and I have had this nagging question that I want to ask. I am sorry but I am not a professional at websites.

My question :

Why is it that the look of a page never matches the look in the editor when you are editing it? The fonts, The width of the page in the editor, the basic layout of the page in the editor.

I have googled this but never found an answer. It seems to me that the editor is not a WYSIWYG editor at all for some reason but should be.

Perhaps I do not use the right plugins after a wordpress install or something? I dont know. Perhaps some kind sole will provide an answer and perhaps some hints on how to work around it a bit.

Thanks,

coffee