An example of <a href="https://en.wikipedia.org/wiki/congruence_(geometry)" class="extiw" title="en:congruence (geometry)">geometric congruence</a>.  The first two figures on the left are congruent.  The third is only <a href="https://en.wikipedia.org/wiki/similarity_(mathematics)" class="extiw" title="en:similarity (mathematics)">similar</a>.  The last object is neither.
Drawn in <a href="https://en.wikipedia.org/wiki/Inkscape" class="extiw" title="en:Inkscape">en:Inkscape</a> by <a href="https://en.wikipedia.org/wiki/User:Ilmari_Karonen" class="extiw" title="en:User:Ilmari Karonen">Ilmari Karonen</a>.  <a href="https://en.wikipedia.org/wiki/SVG" class="extiw" title="en:SVG">en:SVG</a> original available at <a rel="nofollow" class="external autonumber" href="http://vyznev.net/misc/Congruence.svg">[1]</a>.
<p><a href="https://en.wikipedia.org/wiki/User:Ilmari_Karonen" class="extiw" title="wikipedia:User:Ilmari Karonen">Ilmari Karonen</a> at <a href="https://en.wikipedia.org/wiki/" class="extiw" title="wikipedia:">English Wikipedia</a>
</p>
Later versions were uploaded by <a href="https://en.wikipedia.org/wiki/User:Eliashc" class="extiw" title="en:User:Eliashc">Eliashc</a> at <a class="external text" href="https://en.wikipedia.org">en.wikipedia</a>.
Transferred from <span class="plainlinks"><a class="external text" href="https://en.wikipedia.org">en.wikipedia</a></span> to Commons.