Here's a comparison chart for 2DS, 3DS, and 3DS XL:
Source
EDIT: Differences:
- uses an internal rechargeable battery
- battery is in-line with other company handhelds
- charges with the same AC adapter used for 3DS systems
- comes with a 4GB memory card
- built-in speaker is mono, but features stereo headphone jack
- launching in NA and Europe, but not Japan
Source
EDIT: Differences:
- uses an internal rechargeable battery
- battery is in-line with other company handhelds
- charges with the same AC adapter used for 3DS systems
- comes with a 4GB memory card
- built-in speaker is mono, but features stereo headphone jack
- launching in NA and Europe, but not Japan