implement the same python language but execute programs in different ways for examplepypy is drop-in replacement for cpythonwhich can run most programs much quicker similarlyjython and ironpython are completely independent implementations of python that compile python source for different runtime architecturesto provide direct access to java and net components it is also possible to access java and net software from standard cpython programs--jpype and python for net systemsfor instanceallow standard cpython code to call out to java and net components jython and ironpython offer more complete solutionsby providing full implementations of the python language here' quick rundown on the most prominent python implementations available today cpythonthe standard the originaland standardimplementation of python is usually called cpython when you want to contrast it with the other options (and just plain "pythonotherwisethis name comes from the fact that it is coded in portable ansi language code this is the python that you fetch from enthought distributionsand have automatically on most linux and mac os machines if you've found preinstalled version of python on your machineit' probably cpythonunless your company or organization is using python in more specialized ways unless you want to script java or net applications with python or find the benefits of stackless or pypy compellingyou probably want to use the standard cpython system because it is the reference implementation of the languageit tends to run the fastestbe the most completeand be more up-to-date and robust than the alternative systems figure - reflects cpython' runtime architecture jythonpython for java the jython system (originally known as jpythonis an alternative implementation of the python languagetargeted for integration with the java programming language jython consists of java classes that compile python source code to java byte code and then route the resulting byte code to the java virtual machine (jvmprogrammers still code python statements in py text files as usualthe jython system essentially just replaces the rightmost two bubbles in figure - with java-based equivalents jython' goal is to allow python code to script java applicationsmuch as cpython allows python to script and +components its integration with java is remarkably seamless because python code is translated to java byte codeit looks and feels like true java program at runtime jython scripts can serve as web applets and servletsbuild java-based guisand so on moreoverjython includes integration support that allows python code to import and use java classes as though they were coded in pythonand how python runs programs