So we know that Apple (iOS/MAC) is more secure than Windows and Android
Thats not completely true.
While its true that Windows (and android) are both operating systems with a lot of exploits / vulnerabilities, its also worth to note that the majority of users is using these OS.
90%+ of all malware is written for windows. Its true that you won't get 'infected' with the same probability as when using a windows system.
But the actual difficulty of creating malware for iOS is not that much different than for windows.
does that mean bitcoin wallets on Apple phones or MAC are also more securer than their counterparts?
The wallet clients (itself) are usually not more secure on iOS than on windows/linux/..
Its the OS which makes the difference in this case.
I'd say in general (regarding the complete setup) iOS wallets are a bit more
safe than windows wallets. But i'd still suggest linux over iOS.
Or does that make no difference at all?
It depends on the situation.
If you are holding medium amounts and browse the internet often, iOS might be the safer option.
But if you are the target of an aimed attack.. it doesn't make any difference.
If someone want to hack your PC (by knowing you have large amounts, whatsoever..) he will be able to do so regardless of which OS you are using.