Android Archive Library (aar) vs standard jar

AAR files are more similar to Jars than to Dlls for the following reason:

Dlls can be shared across applications where as AARs and jars are
packaged in with your app.

AARs vs Jars:

The main difference between a Jar and a AAR is that AARs include
resources such as layouts, drawables etc. This makes it a lot easier
to create self-contained visual components. For example if you have
multiple apps that use the same login screen, with Jars you could
share classes but not the layout, styles, etc., you still had to
duplicate them. With AARs everything is bundled in one neat package.

In conclusion, AARs are a big step in the right direction.

Note:
Similar attempts were made with apk-libs but they are now obsolete as AARs are much better.