[zokier]

First of all, in Firefox (and I believe in Chrome too) there is a distinction between "addons" (such as adblock plus) and "plugins" (such as flash). The main difference being that plugins are DLLs containing native code, and thus have all the privileges the browser has. In comparison, addons are mostly JavaScript, and run inside the browser with somewhat limited access to the rest of the system.

[anonymfus]

In Firefox extensions have the same access to the rest of the system as Firefox itself including full file system access.

Addons is more generic term, it includes extensions, plugins and themes.

[mariallery]

Thank you for pointing it out and for a well-written explanation. Took a quick look and Chromium seems to call them all 'extensions'.

[aidos]

In Chrome they're different - chrome://plugins/ vs chrome://extensions/