What is the difference between the rose bowl and the national championship?

i know the national championship is between the #1 and #2 teams, but what is the rose bowl.. because last year the rose bowl and the national championship were played as 1 game with USC and Texas
What is the difference between the rose bowl and the national championship?
Actually there are four BCS games (Rose Bowl Pac 10 champ against Big Ten champ, Fed Ex Orange ACC champ against an invited team, Allstate Sugar Bowl SEC champ against an invited team, and the Tostito's Fiesta Bowl Big 12 champ against invited) and one national championship game. Before this year they would rotate and make one of the BCS games the national championship. But in order to give more teams a chance to play in the BCS, they made the championship a stand alone game. They still use the rotating system to decide where they are playing.
Reply:There are 5 Bowl Championship Series bowl games. The national championship rotates between those 5. Traditionally the Rose Bowl is between the Pac-10 and Big Ten champions.
Reply:There are 4 major bowl games or maybe 5, I'm not sure. I believe they rotate each bowl game with the championship. IE: Rose bowl last year was championship, this year maybe sugar bowl is the championship. I could be wrong. Sometimes my memory fails me.
Reply:the national championship rotates between the Rose bowl, orange bowl, sugar bowl, and fiesta bowl last year was the rose bowl and this year its the fiesta bowl the rose bowl is usually the top PAC-10 vs top Big Ten as long as neither is in the national championship since Ohio State accepted bid to the National Championship game Michigan which is #2 in Big Ten gets the bid