The chief difference between Conwy Castle and Caernarfon Castle, is that while Caernarfon Castle is a free-standing structure, Conwy Castle is literally built into the city walls around Conwy. This makes for some very different views.
This is a view of the very prominent bridge leading from one part of Conwy to the castle, itself. However. In a bizarre twist that I could not get a clear answer for, there is no access to the castle from the bridge. Not now, not ever. Talk about a bridge to nowhere, this one leads to a wall. Utterly confusing.
This is a picture of the village just outside the Conwy Castle gate:
The castle walls as they connect to the walled city:
A view from inside the castle:
Current castle resident:
A couple views of the castle, itself:
Conwy Castle is neither as grand or as historically relevant as Caernarfon Castle, but I would definitely recommend a visit if you can. Just the walled structure alone makes for an interesting visit.
Wordsmith Magic 
Pristine, beautiful ancient structures.