What is the difference between iOS and Android development?

Beyond the languages, the day-to-day difference is the release process and the hardware. iOS runs on a small, known set of devices and every submission goes through human review that can reject on policy grounds. Android runs on an enormous spread of screen sizes, manufacturer skins and OS versions, with a faster review but far more variation to test against.

Whichever way the code is written, those two facts remain your problem. Apple's signing and provisioning setup is the single most common cause of a first release slipping, and Android's fragmentation is why a bug report will sometimes only reproduce on one manufacturer's phone. Cross-platform tooling removes the duplicated interface work; it does not remove the review queue or the device matrix.