difference between IDE and SDK (VS and Xcode)

Why for e.g. Xcode is not IDE but is SDK?

or why VS is IDE and not SDK?

Thanks!

An IDE is just an environment
Integrated development environment - Wikipedia, the free encyclopedia

An SDK contains the libraries you need.
Software development kit - Wikipedia, the free encyclopedia

Some have more integration than others, so for example pressing "help" in the IDE, it knows where to go looking in the SDK for the appropriate information.

Xcode is an IDE. You can use it with some SDKs (the iPhone SDK, for example), but it is not itself an SDK.

@tabstop CLEAR! thanks

An SDK is exactly what it says it is: a software development kit. This is an extremely broad term, and has been applied to many sorts of things. It could be a library, a bundle of libraries, an integrated environment, an integrated environment plus libraries...

Apple refers to Xcode as an SDK because that's what it is. A kit of stuff that enables you do develop software. In that sense, Visual Studio is also an SDK, although Microsoft tends to use the term only to refer to the packages of libraries, header files, and assemblies which provide the Windows APIs.

Let's not even get into HDKs, WDKs, XDKs, etc.