Patents are not copyrights. And the infringement of the two things are different. I would agree calling most copyright infringement 'stealing' or 'theft' is technically wrong and sometimes a little hyperbolic.
With patents though, although not physical items, they might as well be, because they are exclusive and can't be duplicated like MP3s or movie downloads. Only one party can hold the patent (unless it's part of an organised group or agreement). So I think it is a lot more like physical stealing or theft.
Apple should absolutely be held to account when they infringe patents too, or else they shouldn't expect to be able to protect their own.
I'd say both of them do come down to an abstract definition of ownership, as neither one of them are actual physical products. Patents are ideas. Clever and innovative ways of doing things. When the system works, the patent holder is allowed exclusive right to their implementation of an idea. If someone finds a way to do something better than what's defined in your patent, then they're not infringing. They've innovated upon your patent, which is a process the system fosters.
When it doesn't work, people are allowed to patent some random vague thing that's ill defined, and basically gives them exclusive right to the idea in its entirety. If you look at some of these software patents, you'll see it's not just the process they have the rights to, but the end results as well. Back in the day, that was verboten in patent law. Not so much now, unfortunately.
Case in point, the Apple vs. Creative lawsuit. Apple lost, and had to fork over half a billion for....what? The UI. And what was the UI like on the old Creative Zen and original iPods? A stack of alphabetized monochrome words you sorted through. It was a text based file system, basically. Apple couldn't make a different implementation of a text based file system for MP3 players, because Creative owned the exclusive rights to the concept.
That's a bit dumb, isn't it? Apple could've used an entirely different backend to produce their file system. Their implementation likely had nothing in common with Creative's. Yet because the end results were the same, they were found guilty of infringement.
But despite all that, does their infringement mean Apple stole? No. It was a vague idea to begin with, and really the only way to organize a music folder for a portable device at the time. They did what they could with what they had. Theft had nothing to do with it. What they did was copy and improve upon the idea, which didn't deprive Creative of anything.
Patent infringement isn't theft.