difference between these two shields

Hi everyone.
I would like to know the difference between
(1)wifi shield from sparkfun $84.95 Arduino Wi-Fi Shield - DEV-11287 - SparkFun Electronics
and
(2)wifi shield from adafruit $39.95 Adafruit HUZZAH CC3000 WiFi Shield with Onboard Antenna : ID 1491 : $39.95 : Adafruit Industries, Unique & fun DIY electronics and kits

Also, the difference between
[1] xbee sheild sparkfun $24.95 SparkFun XBee Shield - WRL-12847 - SparkFun Electronics
and
[2] xbee adaptor adafruit $10.00 XBee Adapter kit [v1.1] : ID 126 : $10.00 : Adafruit Industries, Unique & fun DIY electronics and kits

Looks like the SparkFun WiFi Shield is a clone of the official Arduino shield so it will probably work with the Arduino library and examples. The adafruit shield uses a different chip and would require a different library.

Thanks for replying.

Even if Adafruit CC3000 shield is using different chip and library, will it have the same features like the Arduino shield?
Adafruit is much cheaper than the other. I am planning to use Adafruit CC3000 shield to connect with my android phone.

SparkFun Xbee shield and Adafruit XBee adapter kit? Why is one called shield and the other called adapter? Any disadvantages in using the adapter on an arduino?
XBee Adapter kit again, is less than half the price of the SparkFun shield.

Thanks.

The "adapter" is not a Shield. It does not plug directly onto an Arduino board and establish reasonable connections. To use the adapter you will have to wire the adapter pins to Arduino pins.

vergis:
SparkFun Xbee shield and Adafruit XBee adapter kit? Why is one called shield and the other called adapter?

A shield is made to fit on top of your Arduino, an adapter isn't, although it can be used with an Arduino.

Any disadvantages in using the adapter on an arduino?

Other than it's not a direct plug-in, no.

I have an Official Arduino Wireless SD shield. Is it only compatible with xbee's or will it also work with Zigbee's ?