I was in a lot of confusion about the difference between MGS Ground Zeroes and Phantom Pain. Are these two a different game? Are they one game. Now I understand. I am not smart like many of you. Many of you already have discussed and know what is the real story. But now I came to understand the real difference. In my opinion:

1. MGS Ground Zeroes is a "paid" demo.

2. But this has a different or prequel story to differenciate it from demo.

3. If this is true then this will create a new era of milking.

Source: http://www.metalgearinformer.com/?p=10126

Zeroes is like an introduction to the game as far as I am aware.  I assume it is pretty short since it is cheaper, but think of it this way.  If you want the complete experience of MGSV you will likely need to pay $90.  

Honestly i think it is a tactic to make more money but because I love MGS ill pay for it anyways.

I also love MGS but for me this is kinda like cheating. Now a days game companies are releasing GOTY version and later releasing more DLC for that GOTY version. I was interested after seeing the first demo. But I think I will wait for a complete version. I dont want to get robbed in future by game companies the way I have been robbed in last few years.

Relax, it was like 95% of people who didn't know if they were two separate games, one game with Ground Zeroes as a prolog, if it is MGS V or not, was Phantom Pain - MGS V and Ground Zeroes was not, etc, etc, etc.

Yeah like JayWood2010 said. It's kinda like Ratchet and Clank Quest for Booty. It was cheaper because the game was shorter! It also served as an expansion to Tools of Destruction.

This is like MGS 2 Tanker mission but on a much larger scale

I guess it's not too different from a GT Prologue.

I'm gonna wait until I know how long it is though. No next-gen physical version is putting me down too.

No.

A demo consists of a random section of gameplay from that same game. For example: If I were to go download the Uncharted 2 demo, I would be able to play one (1, Uno) level with no unlocks, trophy support, or save ability. It would most likely be under an hour or two of gameplay at the most. 

If Ground Zeros were a "paid demo" it would be a random section of gameplay from MGSV, with no trophy support, unlocks, or save ability. Also it would last from 1-2 hours.

Ground Zeros will most likely be a 5-10 hour game, WITH unlocks, save ability, trophy support, and probably an online component. 

Were have I been? Exactly when are these games coming out? what platforms?

Metal Gear franchise has been milked for some years now. Konami should stop.