On iOS, the (optional) left action is almost always some sort of “back” – whether to the previous screen sequentially (“Step 2” goes back to “Step “1), or the parent screen hierarchically (“Inbox” goes up to “Mailboxes”). Alternatively, a non-related destination can be linked here. The page title is virtually always present, and starts large, but shrinks with the header as the user scrolls. The optional right page action(s) can be displayed as a single text action or multiple icon actions.
On Android, the page title is left-aligned. There doesn’t need to be anything to the left of the page title, but (a) if the page is a top-level page and there’s a hamburger button in the app, it appears there, or (b) if this page follows another sequentially, you can optionally add a back button.
On iOS apps, primary destinations in the app are listed as tabs across the bottom.
For what it’s worth, many popular third-party iOS apps also conform to a few additional guidelines:
iOS default apps, on the other hand, (1) discourage actions being in the tab bar, (2) don’t have profile- or settings-related tabs, and (3) make search appear last.
The biggest difference on Android apps is that the same primary destinations are more spread out throughout the interface – often between (a) a hamburger button, (b) a search bar, (c) tabs, or (d) a floating action button. We’ll talk about all 4 in later sections. Oh, and note: Android does use bottom navigation more recently, similar to iOS – so you may not have that big of a difference at all.