Yeah, different websites react or push pages different depending on what device you're on. Unless you force desktop mode for all the websites across all devices.
With comparing the iPad and laptop. You have to understand that there is "real" multi-tasking with a computer, where you can have multiple programs running. For the iPad (including iPhone) there really isn't "real" multi-tasking.
Such as right now, I have the twitter application on my macbook pro open while web-browsing. The twitter client on my macbook pro is constantly pushing new tweets to me that are appearing on my timeline, even though my main focus is in Safari, while I have another Safari window streaming video. On the iPad, if I put the twitter client to the background, while my main focus is in the Safari app. I would not be getting new tweets in my timeline pushed to me constantly. I may get a notification if I'm mentioned in a tweet, but that is totally not multi-tasking. And I definitely wouldn't still be getting a streaming video from "window" of Safari (maybe audio, but not video)