On the other hand, there are RADIOACTIVE materials. These include plutonium and uranium (some types more than others), for example. These materials, when they decay, DO emit "radiation", the most harmful of which can be *ionizing* radiation. If these material get inside your body then they will continue to emit harmful radiation, because they are are radioactive. People take supplements like potassium iodide (KI) to block the uptake of a radioactive form of iodine into the thyroid.
Other materials may be only slightly radioactive. For example, radioACTIVE steam was released from the reactors in Japan early on, in an attempt to help cool them. This radioACTIVE material quickly dissipated in the air. The mildly radioactive material is still there, but it spreads out so that it is less concentrated and therefore less harmful in smaller doses.
Here is a summary: Radiation does not equal radioactive. Radioactive does equal radiation.
Radiation itself is not necessarily harmful. Many things radiate (and therefore constitute "radiation"), such as light and radio waves. The "radiation" produced by nuclear (no not nucUler) reactors in Japan, like the light from a light bulb in Japan, cannot travel very far without becoming very faint. Airborne radioACTIVE materials, on the other hand, from the Japanese reactor may indeed travel a much greater distance. A few particles can make it all the way across the Pacific Ocean, though, it is very very very (very very ...) improbable that large number of particles will make it all the way to California. It is far far far (far far...) more likely that the radioactive material which may be released will stay in Japan. For example, when the US bombed Hiroshima (and Nagasaki) we didn't worry about the (don't say radiation) radioACTIVE material from the bomb crossing back over the Pacific Ocean and "getting us". Most all of the radioactive material stayed in a close region around the site of the bomb. We used to conduct above ground nuclear tests in the desert southwestern US. In fact, the first such one was at Trinity, New Mexico. We also exploded nuclear devices on or near islands in the Pacific. All of these threw radioACTIVE materials into the air which circulated all over the place. If we have so much time on our hands that we want to worry about utter nonsense, then it would be better to worry about those, because they produced far more radioactive materials. Chernobyl likewise released a great amount of radioactive material, but not much of it made it to the US mainland.
I know it won't stop the constant, almost intentional misuse of these terms for me to point all this out, but it feels good to do it anyway. In fact, as with "nucUler", people will probably decide to make the mistake more than ever before and push for a redefinition of the terms so that they can finally be correct about something.