What is the difference between c++ and visaul c++?
Visual C++ is an IDE. There's also C++Builder from Embarcadero. (Used to be Borland.) There are also a few other C++ IDE's.
I know that c++ has the portability and all so if you know c++ how is it related to visual c++?
C++ is as portable as the libraries that you use in your C++ application. VC++ has some specialized libraries to use with Windows, so if you use those libraries in your C++ application, you're stuck with Windows. But a simple "Hello, World" application that just uses the console as output can be compiled on Windows, Linux, VMS, AS/400, Smartphones, FreeBSD, MS-DOS, CP80 and almost any other system for which you can find a C++ compiler. Injteresting fact: at http://nethack.org/ you can download the C sourcecode for an almost antique game, where you have to walk through a bunch of mazes, kick some monsters around, find treasures and steal some valuable amulet and bring that amulet back out. (It's also a game where you can encounter your characters from previous, failed attempts to get that amulet. :-) The sourcecode of NetHack is a fine example of how portable C (C++) code can be.
Is visual c++ mostly for online apps?
No. But it can be used for online apps. Actually, C# is used more often for server-side web applications while C++ (VC++) is used for all kinds of (server) components that your application will be depending upon.
Would visual basic be better for desktop applications?
Or Embarcadero Delphi. Delphi and Basic are languages that are easier to learn than C++ and both have very good IDE's to develop GUI applications with. Unfortunately, Visual Basic is now running on .NET only, while there are still many developers who need to create WIN32 applications. Those developers often have to choose between Delphi or C++ or else convince management to move to .NET development.