Let me put it this way.
I am thirsty.
I may want to drink a bottle of lemon juice but I definitely need to drink a glass of water.
Needs are things essential for our very living! Like food, clothing and shelter.
But in this age we have to add transportation to our needs. I may want a car to travel to
my office 20 Kms away, but I definitely need a good public transportation system!!
Some years back people wanted an air-conditioner for their comfort. Thanks to urbanisation, loss of greenery, power-cuts and higher disposable incomes - it is slowly crawling towards a need.