Compiling the source code creates bigger files comparing w/ Ubuntu prebuilt packages, why?

Am I doing anything wrong? I'm building some libraries from the source code, but the file sizes are much much bigger comparing w/ Ubuntu packages. Here is an example.

https://github.com/linuxwacom/libwacom built w/ configure; make creates libwacom.so.2.6.1 (149,1 kB) and the same file in /usr/lib has only 41,8 kB. I assume debug version comes with postfix 'd', am I right - so what's wrong here? Ta.

The shared library is stripped (with dh_strip in the package build rules, which in turn uses the strip command) when the package is built, and Link Time Optimisation (LTO) is also disabled.

You can see the source code for how this package is built on Launchpad. You can also see the source code for dh_strip for more information.