Need tips - buying a PICKUP TRUCK - car?

hi
what is the main differnece between pickup trucks like ford 150, dodge ram givs compared to sedan or SUV in that range.
other than towing capacity.in what other way they coudl be compared to regualr SUVs or 4 door sedan. Will i get the same milesage and driving comfort level with pickup trucks.
basically, what are the pros and cons of a pickup trup compared to SUV or 4 door lengthy sedans.
i am thinking of a switch from my 4 door sedan to a pickup truck. Should i go for ford 150 or dodge ram. My budget is less than 15000 for a used one.in that price range,
what can i expect that i should consider as a better deal.

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