How does AdBlock(Plus) and NoScript differ in the way they block content?

Question

I did a search on the differences between this two add-ons, but I only find dull and basic forum threads.

From what I understand Adblock(Plus) use some kind of regular expression to disable content, but doesn't prevent say content to be loaded. While NoScript prevents pages from loading untrusted resources (so should increase page loading).

Question

So could someone explain the mechanism behind each of this add-ons and their impact on network traffic ?

Please provide sources in your answer.

Answer 1

AdBlock(Plus)

From the wikipedia article AdBlockPlus:

allows users to prevent page elements, such as advertisements, from being downloaded and displayed.

From official website section How does Adblock Plus work?:

it can block specific requests from websites, usually the requests to serve an ad.

NoScript

From NoScript website section Beyond JavaScript: blocking Java, Silverlight, Flash and other embedded content :

Java Applets, Flash movies/applications, Quicktime clips, PDF documents and other content won't be even downloaded from sites where you consider them annoyances or dangers, saving your bandwidth and increasing your navigation speed

Also as shown in The test: The effect of Firefox addons on bandwidth consumption, NoScript effect on bandwith is a lot more significant than AdBlock-like add-on.

Conclusion

So it seems both use the same mechanism to prevent ads to appear.

Answer 2

AdBlock will indeed prevent files from being loaded. You can see this by looking at the Network tab in a browser's debug tools. The fact that it failed to load means it was blocked entirely.

NoScript prevents javascript from running at all, except for trusted sources, so it will break a lot of websites that depend on JS for daily interaction. If you're ok with constantly whitelisting things, it can have a larger impact on page loads (in a good way) but at a risk of lost functionality.

edit: this post was made referencing AdBlock, not AdBlock Plus, as it was written pre-edit. Point still stands regarding that software.

Answer 3

Big difference, I don't trust NoScript, they have been caught breaking Mozilla rules on more than one occasion, most recently modifying NoScript so it disables the Ghostery plugin when viewing the NoScript website. Another of note is, using Adblock Plus, I successfully blocked third party iframes, when NoScript was installed, for some reason, third party iframes were allowed again, whether NoScript disables just part of Adblock Plus or all of it, I have no clue, I don't know enough about programming to say either way.

If anyone more knowledgeable than myself can tell for sure, here is how to reproduce my results first add this rule to Adblock Plus, *$subdocument,third-party, this blocks third party iframes, than install NoScript and make sure javascript is disabled for ip-check.info, it must be disabled, for some reason, NoScript blocks third party iframes itself if javascript is enabled but not if it's disabled for that page, which by itself is a little peculiar, but anyway do a check, with just addblock plus enabled, authentication (third party frames) will be green (good), soon as you install NoScript, authentication will now be red (bad) for some reason NoScript disables part or all of adblock plus.