What's the difference between the iPhone 4 and the 4S?

Am looking on the apple website and the 4S is over 100 more than the 4. What's the main difference in both? Is it worth spending the extra money for the 4S?

Never had an android/smartphone so i wouldnt really know if its the best or not, anything is better than this old phone i have now. Opinions please haha, thanks.

4S Has Siri

THE SMART PHONE IS VERY HARD TO UNDERSTAND All OF THE FEATURES.;. I FOUND OUT HOW TO SEND A TEST BY TALKING INTO THE FONE AND IT TYPES FOR ME.SAFER THAN TEXTING WHILE DRIVING.

QUITE COMPLICATED… I OWN A SAMSUNG CHARGE… VERIZON… I INTEND TO GO TO THE WORKSHOPS… CLASSES… VERY INFORMATIVE, I HEARD… THE BATTERY DISCHARGES BY MID AFTERNOON EVEN THO I DON'T FEEL I USE IT THAT MUCH.VERY ANNOYING… GOD BLESS U I HEARD THAT THE NEW IPHONE HAS "TWO BRAINS" AND THE OLD ONE HAD ONLY ONE BRAIN… I GUESS I HAVE NO BRAIN SINCE I FEEL So STUPID WHEN I USE MY FONE…

Siri - Personal Assistant
A5 Chip - Faster than A4 on iPhone 4
Slightly longer battery
Better back camera
"4G" it's really slightly faster 3G (AT&T model only)
4S is a real world phone

I would go with the iPhone 5, since it's just $200 and it's VERY GOOD!