Xd card and sd card are the same?

the memery cards mentioned above are used in digital camera, which one is better? and can they be interexchanged?? thanks

No, different sizes. Find the exact one that fits your camera.

Ok I did more research. If you havent bought the camera yet, dont buy the one that use the xd. You will have a hardertime finding xd readers, thats why.
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XD is actually the brain child of Olympus/Fuji.. and ONLY Olympus and Fuji use them.
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SD readers are universal and you can download your pictures anywhere. ok?

theres not much significant difference in them besides size and stuff. id go with sds though cuz they seem to be more common for digital cameras and stuff

Different camera manufacturers use different memory cards.
xD is ONLY used by Fujifilm and Olympus
SD is used by many other brands (it's the most popular)
MemoryStick is ONLY used by Sony
CF is now mainly used by digital SLR cameras

They cannot be interchanged.