The European giants clash in preseason on Wednesday and though they both have similar aspirations heading into 2014-15, the Partenopei coach acknowledged the economic gulf.
The Serie A giant faces Barca on Wednesday in a friendly as the club's continue their build to the 2014-15 season and Benitez made no attempt at claiming his team can stand toe-to-toe with Luis Enrique's men, with the Spaniard pointing to the economic gulf between the sides.
"In my opinion, there is a difference in principle with regards to the expenditure of the two teams," he told reporters. "I think it's about €500 million.
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"Napoli have a strong balance sheet and it will certainly improve with time, but today our financial potential is miles behind that of Barcelona. For this reason, mainly, perhaps the gap between the two teams remains remarkable. It will be a prestigious challenge against a team which have plenty of quality."
The Spaniard was also non-committal when asked whether Gonzalo Higuain will feature against the club he was linked with earlier in the summer.
Benitez said the striker "is eager to return but he is not yet at 100 percent" after Argentina finished as runner up at World Cup 2014.