Just running down the main featurelist here.
Friends List/Matchmaking
Xbox Live: Yes
NWC: Yes
Stat Tracking
Xbox Live: Yes
NWC: Yes
Messaging
XBL: Yes
NWC: Unconfirmed as a standalone feature, Animal Crossing allows it in-game.
Voice Chat
XBL: Yes
NWC: No
Downloadable demos
XBL: Yes (Xbox 360)
NWC: Unconfirmed, although with the usage of wifi hotspots to deliver demo content in the past, it looks likely.
Content downloads
XBL: Yes
NCW: Yes
Feedback System/Bans
XBL: Yes
NCW: No/Unconfirmed
Online awareness in non-online games
XBL: Yes
NCW: No/Unconfirmed
Price
XBL: $50/year
NCW: Free
Friends List/Matchmaking
Xbox Live: Yes
NWC: Yes
Nintendo's unique new Friend Roster enables players to play online with their friends, all you need to do is set up a Friend Code by swapping a number with your friend, they will then be added to your Friend Roster and you can select to play with them online anytime, anywhere. Alternatively you can play with someone of a similar skill level. This is done seamlessly via Nintendo's servers through the use of a skill mapping system to ensure the environment is open to users of all ages and skill levels.
Stat Tracking
Xbox Live: Yes
NWC: Yes
Activision's Tony Hawk's American Sk8land will let players compete head-to-head in multiplayer games in a variety of modes. Players also can create custom skateboard art and graffiti tags, and share them with other players via Nintendo Wi-Fi Connection. The service will track global high scores and stats. Tony Hawk's American SK8Land will launch on Nov. 14.
Messaging
XBL: Yes
NWC: Unconfirmed as a standalone feature, Animal Crossing allows it in-game.
Voice Chat
XBL: Yes
NWC: No
Downloadable demos
XBL: Yes (Xbox 360)
NWC: Unconfirmed, although with the usage of wifi hotspots to deliver demo content in the past, it looks likely.
Content downloads
XBL: Yes
NCW: Yes
Activision's Tony Hawk's American Sk8land will let players compete head-to-head in multiplayer games in a variety of modes. Players also can create custom skateboard art and graffiti tags, and share them with other players via Nintendo Wi-Fi Connection. The service will track global high scores and stats. Tony Hawk's American SK8Land will launch on Nov. 14.
Feedback System/Bans
XBL: Yes
NCW: No/Unconfirmed
Online awareness in non-online games
XBL: Yes
NCW: No/Unconfirmed
Price
XBL: $50/year
NCW: Free