Need - More important than want because it can become something you need to live and breath.
Want - You just want something for no reason or it doesn't have a better reason than what you need.
Explanation:
Example
Need - I need water or I will die.
Want - I want a 40 in tv to play Fortnite on a bigger screen.
Want
Its like asking your mom "can I have a lollipop because it looks good" and she says no because you don't need it.
Need
Its like asking your mom "can I have socks or underwear because they don't fit or there broken" and she says "yes because you need em obviously or your nasty.
One main reason why John C Breckenridge supported the purchase of the Louisiana territory was because he thought it would held end the issue of slavery, by leaving it up to "popular sovereignty" in the new territory.