What differ *.stp and *.wsp Windows Sharepoint Services files?

"A .stp (site template) file contains resources and a manifest file
relevant to an individual site template, and is limited in that it
only contains a site itself with lists, etc.  SPS 2003 and WSS 2.0
used .stp files, and they can still be used in MOSS 2007 and WSS 3.0.
They are convenient, in large part because a relatively inexperienced
user can save a site to template through the UI, and create new sites
from that template with no knowledge of the .stp file's contents, etc.


A .wsp (solution) file similarly contains resources and a manifest
file, but is more broadly used for extending MOSS 2007 and WSS 3.0
(not applicable to SPS 2003 or WSS 2.0), and is generally used for
deploying Features, which can consist of site definitions, lists, web
parts, custom actions, fields, etc., etc.  It is much more extensible
than the .stp framework, though it is also therefore more complicated
to use.