Will Iridium make a difference over Platinum plugs in 2005 Sentra with normal driving?

Will there be a difference, in terms of fuel economy and longevity and reliability of both the plugs and the engine, between using Iridium or Platinum spark plugs in my 2005 Nissan Sentra 1.8L? I am trying to decide between two NGK plugs, and I am willing to spend the $8 difference if it makes a difference in fuel mileage or plug and engine longevity and reliability. Which should I get?