Briefly, pkgsrc is quite similar to both, in that it allows you to build software easily from source.
This repository is a bulk build of all available packages in pkgsrc, so it gives you the option to install from binary packages instead of having to compile them from source. However, you still have the option to build from source if you prefer, or want to select different compile options from the defaults.
It also comes with 'pkgin' which is very similar to 'apt-get' and allows you to quickly search, install, upgrade and remove binary packages.
This is the same framework we use for SmartOS, so if you provision a SmartMachine from Joyent you get the same interface. pkgsrc is cross-platform, so you can use it on Linux, OSX, Solaris, *BSD .. or even more exotic systems such as Cygwin or Haiku.
If you have any comments/complaints I'd love to hear them, we want to provide excellent packages.