The goalkeeper said his side were in a process of transition heading into last year's game in Turin, which took place little more than two months into the reign of new coach Gian Piero Ventura, and where Spain had 71 percent possession but Italy grabbed a point with a late Daniele de Rossi penalty.
Since then, Italy have won four qualifiers out of four, scoring 14 goals.
"The first game had nothing to do with what will happen tomorrow, we have worked hard for a year to reconstruct the team and we have changed," Buffon told a news conference on Friday.
"We have seen different things in the last year in training, we hope tomorrow that difference will give us a good result. Leaving this stadium with a victory would be a huge injection of confidence for us."
Both sides have 16 points with four games remaining, and coach Ventura admitted the winner of Saturday's game is likely to finish top of group G and qualify automatically for next year's World Cup in Russia.
Italy were dealt a late setback on Friday with veteran defender Giorgio Chiellini being unable to travel due to a calf injury, although Ventura said the centreback's absence will not affect his plans for the game.
He also said his side would not be unnerved by the atmosphere of a sold out, 85,000 capacity Bernabeu willing on Spain to victory.
"Chiellini's injury isn't good for us but it won't change the decisions I have already made. It hasn't changed anything, all it means is we've lost a very important player," Ventura said.
"We are expecting a huge game against important players in a big stadium so we'll have to be fully focussed. But despite everything I've been out on the pitch and I didn't see any snakes or any crocodiles, just the pitch and some goalposts.
"The problem is we'll have to face opponents of the highest quality but in the end it's a game of football, you always have the chance to get the result you want against any side if you do things the right way."
(Reporting by Richard Martin; Editing by Christian Radnedge)
