Under IOS, apps aren't kept in an ordered system collection the way they are in Android. If they're on the device at all, they're somewhere on a page or within a folder, either where you put them, or where the system put them (always on a page) if you have not interfered. And finding them, if you don't know where they are, is a matter of typing the name into the search.
But -- just like Android -- you can have a lot of pages, a lot of folders, and you may or may not remember where a particular app or shortcut is located in your own personal folder/page setup. But then there is IOS search, which can find anything.
Under either OS, if you can't remember where they are, and you can't remember the name, it's down to looking around until you find them.
One of the arguments for folder organization is that if you even know the type of app it is -- for instance, if it is a photography app -- then if you're consistent at install time, you can look just in there, and it will be there, leaving you a lot fewer apps to check through until you find it.
But IOS has low limits on how many apps can be in a folder, and it doesn't allow subfolders, which seriously impacts how well you can really use them for that kind of organization. In my case, IOS's folder paradigm is insufficient to my needs. Android isn't significantly better, either.