What's the difference between Wifi and Bluetooth?

"Wikipedia has good articles on both 802.11 WiFi technologies and Bluetooth technologies.

Wikipedias quick summary of the differences:

Bluetooth and Wi-Fi have many
applications in today's offices,
homes, and on the move: setting up
networks, printing, or transferring
presentations and files from PDAs to
computers. Both are versions of
unlicensed wireless technology. Wi-Fi
is intended for resident equipment and
its applications. The category of
applications is outlined as WLAN, the
wireless local area networks. Wi-Fi is
intended as a replacement for cabling
for general local area network access
in work areas. Bluetooth is intended
for non resident equipment and its
applications. The category of
applications is outlined as the
wireless personal area network (WPAN).
Bluetooth is a replacement for cabling
in a variety of personally carried
applications in any ambience.

So basicly, 802.11 is an addition to the networking and connecting of computers & smartphones supporting high-bandwidth, and covers large areas.

Bluetooth is a ad-hoc wireless technology which works at low distances, making it perfect for file tansfersing and remote-control hardware."

When most people talk about "wireless" they are probably talking about a particular wireless protocol called IEEE802.11 which is used for wireless networks. Bluetooth however is an alternative wireless protocol and is typically used for short range 1-1 communication and was originally designed as a wireless replacement for RS232 serial cables.