Intelligent Devices are the embodied equivalent of Intelligent Agents: narrow machine intelligences that have great competence in a single domain, and no other skills. An intelligent device can do one IRL thing very well.
Almost every machine and tool has some form of integrated intelligence that makes it operate more effectively. Your fridge isn't an Intelligent Device because it can browse the internet. It's an ID because it keeps track of what's in it, what's getting ready to spoil, and what's running out. Your IAs talk to the fridge and the grocery to make sure that the right stuff gets delivered daily. In most cases there is no need for a physical interface: you communicate through your AR. For example, you might wake up, put on your AR glasses, stretch and ask, "Jarvis, what's for breakfast?" Your IA talks to the ID, consults the AI about what you want compared to what you have. A moment later it says, "Your options include last night's pizza, eggs and bacon, and a handful of cashews as you rush out to the meeting with Nancy." Unlike IOT devices, IDs are more generally capable of interacting with the world like animals and humans do. The Roomba is recognized as one of the first IDs. Now many homes have IDs that cook, clean, do laundry (including folding and putting away) and so on.