1 What is it, exactly, that makes the spider-walk different from the insect walk, so much so that it's instantly identifiable?

The interesting thing about the "cat frightener" is that it looks like the operator generally doesn't directly control each individual servo, but instead issues high level commands: "Up" "Forward". "Back".

That suggests that the spider-walk arises from the motion-rules the hexapod is programmed with.

What's different about the rules that would result in an insect-walk?

Hm, maybe it's not the rules. Is it the way the legs are jointed?

2 Now they just need to make it autonomous:  infrared sensors, a command to 'approach' warm mobile objects, and perhaps some sharp pointy venomous fangs. . .

3

I think a spider's legs are perceptibly more radial than an insect's legs. All the legs on an insect join the body near one another, but they don't angle as much and there's more of a perception that they're in-line.

When a spider is standing still on a flat surface, the 8 points where it touches the ground will be close to circular. For an insect, they'll be six points on a very long oval which would extend far beyond its front and back.

A spider can spin in place. I'm not sure that's a natural motion for an insect.

4 Here's the original page. One of the really, really cool things is that the servo control sequences are created using an Excel spreadsheet.

5 Ah. Another difference in our perception between spiders and insects is that all of a spider's legs are about the same length.