gh-154388: Document Python install variants

Author: BHUVANSH855

Doc/using/windows.rst

@@ -272,6 +272,12 @@ New runtime versions may be added using ``py install``. One or more tags may be
 specified, and the special tag ``default`` may be used to select the default.
 Ranges are not supported for installation.
 
+CPython publishes multiple runtime variants. ``PythonCore`` contains the
+standard CPython runtime. ``PythonTest`` additionally contains the test suite
+and debugging symbols. ``PythonEmbed`` contains the embeddable distribution for
+bundling Python into another application. These are variants published by
+CPython rather than features of the Python install manager itself.
+
 The ``--source=<URL>`` option allows overriding the online index that is used to
 obtain runtimes. This may be used with an offline index, as shown in
 :ref:`pymanager-offline`.