ios

As far as the version is concerned, both support the current one (now 14.4).

But iOS (for iPhones) and iPadOS for iPads.

Regards

Giulio

Whilst iOS for iPhone and iPadOS for iPad are very closely related, there are considerable functional differences.

With the introduction of iPadOS13, Apple have expanded capabilities of iPad to capitalise on the larger screen and multitasking capabilities of iPads higher performance processors.

Older models of iPad, too old to be updated to iPadOS, run iOS12 and earlier. These versions of iOS for iPad still have minor differences, but are essentially the same OS with almost identical functionality.

If you're talking about Apple's applications, that's by design. For example, Weather runs only on iPhone. So does Calculator.

If you're talking about third party applications, that's by design also.