There are of course differences. The notifications bar works like a cross between Android's and the new one in iOS 7 that Apple has demoed widely. Swiping to the leftmost screen opens not the search bar for your device but for the Firefox app store.
All in all, the Firefox OS hangs together sensibly. It's less sophisticated than the beta Ubuntu Touch OS but serviceable.
However, the Firefox OS shows way too many rough edges once you start using applications, and the very cheap hardware from Chinese manufacturer ZTE doesn't help either: The touchscreen is not very responsive, for example, so device interactions are difficult. Good luck typing in complex passwords! And boy, is the device slow, even for simple tasks like opening emails. Don't expect to finish every action; trying again is part of the experience.
But the cheap hardware isn't solely to blame. The HTML5 software that comes with Firefox OS, as well as the very limited set of apps in the app store, reinforce the notion that you can't do serious apps in HTML. Whether the fault lies with HTML or with the developers, the result is a smartphone that is not smart and is barely better than the so-called feature phones intended to provide only a modicum of functionality.
For example, no Firefox OS app that I tested supports text selection or copying. Then again, no apps I tested supported text selection or copying. All you can do is tap where you want the cursor location to be, then add text or backspace to delete text one character at a time -- seriously.
The Mail app supports just IMAP accounts, though it doesn't see all your mail folders. There's no POP support, and the ActiveSync support doesn't work with Microsoft Exchange, but just Hotmail and Outlook.com accounts; don't even think about accessing corporate email. If you want to add an attachment to a message you're composing, dream on -- you have to go to an app such as Gallery to select and share the app via email. There's no formatting for message text such as boldface.
The Calendar app supports Google Calendar, but that's it. And forget about repeating events or issuing or accepting invitations. The Contacts app supports no server-based contacts, just what you enter manually or have on a SIM card. The Messages app supports only SMS messaging, none of the free and popular instant messaging services.
The Firefox OS and its built-in app suite simply can't be used for business, even for small businesses relying on the Google Apps capabilities that nearly every device out there supports via native client or Web browser.