EDT meaning Eau De Toilette is a solution of between 4 and 8 percent perfume oil in alcohol.
if you mean 'perfume' by EDP, meaning Eau De Parfum is a solution of 15 to 18 per cent perfume oil in alcohol. most of the time, Eau De Parfum is more expensive compared to Eau De Toilette and Eau De Cologne because it contains considerably more perfume oil
for an example :
100ml EDT  Dior Homme Sport : RM 272
100ml EDP Dior Homme Intense : RM 303

another good comparison would be Yves Saint Laurent La Nuit De L'homme. the EDP would be more expensive than that of an EDT for that matter.

in terms of which last longer? well, there is no definite answer to that. just because EDP have more perfume oil in alcohol doesn't mean it last any longer.
for an example, Jean Paul Gaultier's Le Male (EDT) will last me a whole day of wearing and projects like a monster but that at the same time, a Creed Silver Mountain Water will not project as loud and last as long even though Creed Silver Mountain Water is an EDP concentrate.

to my nose, most EDP fragrances smells more natural than EDT. meaning, less synthetic. less generic. a EDP vanilla will smell more like a real vanilla I smell in real life compared an EDT vanilla. say, Dior Homme Intense's vanilla is more natural compared to Le Male's vanilla. not a fair comparison, but well, just for you to get the idea.
for best experience, go to a Diptyque booth. most to of their fragrance they will have two concentrations, an EDT and an EDP. smell both out. to me, well, to my nose at least, I get a closer to natural scent out of their EDP's. I think I was smelling out Volutes.

hope this helps!