they're in freefall, when they are orbiting the earth. I'm not certain of this, but think of this: When you jump out of a plane and skydive you are in freefall but it's a different freefall because you are experiencing wind resistance. Now, if you are in a large box and fall out of a plane, you will feel the kind of weightlessness that astronauts feel because you wont feel any wind resistance (friction).
So, when astronauts freefall they are in an orbitter which is falling towards earth, they dont freefall like a sky diver because they are inside, and when outside they wont feel it because there is less atmosphere and wind resistance.
The fact that an orbitter is constantly falling towards earth is difficult to understand - think of this - When you throw a tennis ball, it will follow a parabolic path and fall to the ground. When you throw it faster, it travels further, before hitting the ground. What if you could throw the tennis ball so fast that it falls off the edge of the earth? It's parabolic path is so large that it falls off the end of the earth - it wants to fall to the ground, but as it tries it just keeps falling off the edge of the earth, and hence is in an orbit. Think of this at a human eye level on Earth.
hope this helps
