When is a robot not a robot?

I know, it's not exactly a pressing philosophical issue. But my question is not, I would argue, an idle one. It arose after seeing the summer's two most recent action thrillers, "Pacific Rim" and "The Wolverine," both of which feature giant mechanized figures. In the first movie, the futuristic plot revolves around machines called Jaegers, which have been built to combat a race of Godzilla-like monsters. Like all Jaegers, the main one, called Gypsy Danger, is considered a robot.

(Warner Bros. Pictures)

In the second film, the titular Marvel Comics hero, played by Hugh Jackman, travels to Japan, where, in a climactic scene, he does battle with something called the Silver Samurai. Although it looks very much like a robot, it's actually a souped-up suit of armor, with hydraulics and other electronically controlled parts. Both of these machines — for that is what they are — have people inside them.

(Twentieth Century Fox)

So why is one a robot and the other one not?

First of all, "Pacific Rim's" skyscraper-size Jaegers are huge, relative to the size of the pilots, or Rangers, who operate them from control rooms, or Conn-Pods, inside the machines' heads. Although the Silver Samurai is a lot taller than Wolverine, it's still closer to something you wear — a form-fitting suit of powered armor, like Iron Man's costume, say — than to something you drive. Think of it this way: In scale, it's akin to the AMP suit (for Amplified Mobility Platform) that the bad guy Col. Miles Quaritch wore in "Avatar." Personally, I think that thing was starting to get into robot territory, but that's just me.

Some purists might argue that neither Jaegers nor the Silver Samurai are, strictly speaking, robots since unlike Transformers, they are both controlled by humans. Perhaps a better classification is what the Japanese call Mecha (short for the word mechanical). Though Mecha don't typically include powered suits of armor, the category is useful to describe an increasingly fuzzy — and increasingly popular — genre of movie machines, where humans take a back seat to hardware.