The process of activating a Titanium Apple Card differ based on model of iPhone.
Specifically, for a 2018 iPhone (iPhone XS/XS Max/XR), one is required to open the Titanium Apple Card packaging, wake the iPhone and hold it near the card. While, for a 2017 or earlier (Apple Card supported) iPhone (iPhone X or earlier), one is required to launch the Wallet app to activate the physical card.
From the Apple Support document, Request and use your titanium Apple Card:
How to activate your Apple Card
You need a compatible iPhone with the latest iOS version to activate your titanium Apple Card. When your titanium Apple Card arrives, it's easy to activate.
Activate on iPhone XS Max, iPhone XS, and iPhone XR
Watch the video to see how to activate your titanium Apple Card >
Open the packaging that has your titanium Apple Card inside.
Wake your iPhone and follow the instructions inside your card holder.
Tap Activate.
Activate on iPhone X or earlier
Watch the video to see how to activate your titanium Apple Card >
Open Wallet on your iPhone and tap Apple Card.
Tap Activate Your Card.
Wake your iPhone and follow the instructions inside your card holder.
Your card is ready to use as soon as it's activated.
What specifically is the difference in terms of hardware (or software) between 2018 and earlier iPhone models which necessities the difference in activation process?