How does the Lightroom iOS IAP 100GB subscription differ from the 20GB one?

There are three different Lightroom subscriptions available on adobe.com. Easy enough.

But then there's a fourth one available as In App Purchase in the iOS app.

The IAP subscription is by far cheaper option and with 100GB storage.

is it just the LR Only option but with a lower storage capacity?

Or are there other caveats?