What's the difference between Attack IV's and Attack EV's?

I'm playing Pokemon Yellow. Now my Pikachu is at level 7. He has 24 Hit Points now, has an attack power of 14, defense points are at 11, speed is at 18, and special is at 13. Since we can't see the IV's but the EV's what's the difference between them? Another question: Are Ev's the things like tell you your Pokemon has earned 434 Experience Points, and it needs 78 more points to reach level 8, etc?