I've been working with ionic for a short while now and across various literature I've seen both of these commands used to add the android platform.
Could some one please tell me the difference between using the two vis-a-vis what advantages/disadvantages are offered and which one one should typically use?
The only big difference that I know about is that the ionic variant of the command adds the plugin as a dependency in package.json and the cordova command does not. It is advantageous, because it ensures that your package.json is kept up to date, but if you just want to try the plugin for yourself, you can decide to use the cordova command.
That really seems to be the only big difference, but feel free to take a look at the source code here.