definitions definitions definitions

What's the difference: a Masters degree vs a Graduate Diploma?

Apparently a Masters degree is worth more than Grad. Dip. it seems. But why then, are Masters courses in town made available for completion in possibly one year, whereas the latter can take 3 years?

I'm inclined to translate the definitions based on what I've learnt from people around me. That a Grad Dip falls between a Masters' and a Bachelors' degree. And it comes with more specialisation. So it seems to cover more depth than breadth. But yet the Masters' would seem to be more high level.

Is this something like mobile phone networks, where a Bachelor is 2G, the Grad Dip a 2.5G, followed by a Masters being 3G?

Or can I otherwise liken it to part of our Singapore tertiary education system? Bachelor = Secondary school, Grad Dip = ITE, Masters = Polytechnic, Doctorate = JC? How are these things being assessed and valued by companies locally? I'm perplexed.

I'm still shopping around for a good postgrad course to take up, when I came across the above. If you have any (part-time ones) to recommend , do tell. I'm still trying to weigh cost/quality for what I've collected thus far.

INSEAD/Chicago GSB are of the BMW/Mercedes price range, whereas SIM/Kaplan/SMU are the Toyota/Honda price range.

Yes I realise I like to do analogies. Paints pictures better that way, I noticed.