Yes they are different.
View source shows you the original HTML source of the page.
The inspector shows you the DOM as it was interpreted by the browser. This includes for example changes made by javascript which cannot be seen in the HTML source.
Oh and this also counts for the developer tools that allow you to view the DOM in other browsers, like the Chrome Web Inspector and Internet Explorer Developer Toolbar. The HTML source will always be the same across all browsers, the generated DOM might differ as it is an interpretation and render engines are not all the same (unfortunately).
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…