JK2 has answered your question but I wonder if you've been looking at the 'Barcelona' airports listed on the Ryanair website. If so, there's very little difference between the two. (The coach takes 'an hour and a bit', depending upon traffic conditions, from both Girona and Reus).
However, as JK2 indicates, the 'true' Barcelona airport is much closer to the city:
http://www.aena.es/csee/Satellite?pagename=Est andar%2FPage%2FAeropuerto&c=Page&Language=EN_G B&MO=0&SMO=-1&recortar=0&nombreSelect=vaereo&S iteName=BCN%26cid%3D1045569607459
(Information for Girona & Reus airports can be obtained by using the pull-down menu on that site)
Chris