C++, Java and C# are compiled languages. That means, they code you write in these languages are compiled to bytecode by a compiler (which adds some optimization of its own) and the bytecode is run on the machine. Python is an interpreted language which basically means code is converted to bytecode as it is executed and there is no compilation whatsoever.All except C++ ship with a Garabage collector to manage memory. In terms of performance, C++ is blazingly fast and Python is very slow. The performance benefit with C++ comes is due to it being low-level and comes at cost of not having a garbage collector by default (which could be good thing or a bad thing depending on your requirement). As a basic principle, you can make almost any application using anything programming language. But some PLs are geared towards certain domain than the others. As such, C++ is used in for systems programming and performance critical applications (e.g Operating Systems, Adobe Photoshop). Java and C# can be used for developing almost any kind of app (web, desktop, mobile) but Java is more popular among Android developers. Python is mainly used as a scripting language and for scientific computing due to its simplicity and huge number of libraries (e.g numpy, scipy, pandas...etc)