What's the difference between the Iphone 4 and the newest version Iphone 6?

I ordered this one just recently…

http://www.amazon.com/...005ZD6WQS/

I mean I wanted to get the cheapest Iphone they had available since I can't afford the much newer, expensive ones they make nowadays. So will I still get mostly everything I want on this old one and what's the difference between this older model compared against the newest one? Will I really be getting my money's worth? How long ago was the version I'm getting released? I'm just curious. Please just tell me what I'll be getting and what I won't be getting.

Why would you get an iphone on a low budget?
Get a samsung.
But you ordered it, and now you ask what to buy?
Wrong order.
As for apple, you never get your moneys worth i.m.o.
It is stylish and easy though.

For the record the iPhone 6s is the latest model

Yes you would for the most part get what you want.
Could compare the 2 at GSMArena.com
Again for the most part yes
iPhone 4 came out in 2010

With iphone 5S free on contract, why would you not do that deal? Thats also a big upgrade over 4, much better hardware.