@slibuntu: No, there *is* a difference. It all depends on the particular license.

The restrictions regarding use of open source code depends on the particular license. Some allow any usage, some allow commercial usage only if modifications to the code are given back to the community, some allow no commercial resale of any part of the code.

In the case of Apple, they are allowed to use the underlying open source code and *do* give back changes to the community. On top of that underlying FreeBSD (IIRC) open source software sits the bulk of OS X (which is not open source). There's no violation there.

You do NOT have to make all your code open source just because you use some open source code in your product. That's a bit of FUD that Microsoft spread a while back in hopes of getting businesses to avoid Linux.