Well, a plug in and an embedded object are two completely different monsters.
<edit> One runs client side while the other runs server side, for example. </edit>
They both run client-side- an embedded object basically embeds a music file, a picture, video, etc, into a page, and let's the browser figure out how to handle it. but whatever it decides, will be on the client side- for example, with embed, it doesn't work in either FF or Opera without a media player plugin; Internet Explorer uses Windows Media player by default. an embedded object could be said to be data that may (or may not) require a specific type of plugin to use. for example, you could embed an XML document, but it won't do a lot of good unless the browser knows how to deal with it.