I understand the copyright infringement and stealing are not the same but how is that? You are taking material that isn't yours (copyrighted) and that isn't open source and using it. But then again what is the difference if you watch a video on youtube, as previously mentioned, or borrow a friends DVD or video game. Is it because you are "borrowing" and not "keeping". This is where, like you said, ethics come into play.
Legally defined, 'theft' is deprivation of another's property, and requires that
they no longer have it in their possession because it was taken by you - copyright infringement, on the other hand, is an intellectual violation, and applies to a lot of other scenarios. So while the basic 'it's not yours to do with as you please' baseline is still there, the suitability of the language used to describe it (which is how sentencing is handled in a court case) depends on the material specifics involved.
Unauthorized copying would be the most relevant point to contrast theft and infringement, but it can even ostensibly include something like lending someone else a recording of a TV program you made - strictly speaking, you are the only one authorized to view it, as you made the recording; at the most permissive, maybe it applies to just within your residence, as it was made there and meant for private use only. This is perhaps the most obvious example of an interpretation authorities scoff at, because it's ridiculous, sort of like weird traffic laws that you can't leave your elephant 'parked' - or whatever the term is - on Main Street*; but unauthorized public display (again a form of copyright infringement) is just that idea taken to its most extreme conclusion. There's a dividing line there, and there's often no real telling where it crosses that line. Some things are clear-cut violations, and others are not. Theft is mostly clear-cut, although there's some grey areas in it, too - such as someone stealing property from you, and you taking it back from a non-involved third-party without alerting the police to the situation so they can legally handle repo-ing the goods. At least, that's one case I would assume where theft isn't so black and white - 'two wrongs don't make a right' mentality, basically.
*there really is a law similar to this on the books in the city I live in, if I remember correctly.
Lending, exhibition, parody, reverse engineering, and other things may or may not be protected under the law, and it mainly has to do with fair use, private use, anti-trust/cross-compatibility, etc. provisions. The bigger problem is that while such provisions do exist, they are not very well-defined, and there are practically as many circumstances to try (that's legal 'try', as to make clear in court) them under as there are circumstances to claim them for.
The actual legality and nonlegality of something also changes from country to country and how they apply and interpret their own copyright laws. It's that nebulousness to licensing and copyright that underlies the reason that Ubuntu doesn't include certain things like MP3 or DVD playback by default (as some countries' laws wouldn't allow it while others' would), or why Microsoft cannot include Windows Media Player in copies of Windows sold in Europe (although European users are free to go download WMP and use it if they want to - but it can't be there from the start due to the anti-trust lawsuits Microsoft lost over there).
