MacPorts just like ports on any BSD type systems (NetBSD uses different terminology but pkgsrc is essentially what Free, Open, Mir people call ports) is just a collection of Makefiles which will fetch source code, patch it as needed, resolve dependencies, compile, and install package for you. Unlike regular Mac packages which are installed in small containers packages compiled from ports use shared libraries. That is why they tent to be much smaller than the regular Mac packages which are self sufficient. I am an OpenBSD guy with very little experience on Mac. In my experience MacPorts some times do not play well with Aqua and some GUI systems tools. Also in my limited experience for things like TeX you are better of to use native Mac package than the port. Native package tent to be more quickly updated. I would limit MacPorts use to the things which are not available as Mac packages. For Mac I would definitely go with the "official" MacTeX distribution.