Nope..not even close to the same thing. The only similarity is that they're all park skis. Let's examine, shall we?
THalls are made in Slovenia(correct me if I'm wrong, either way, it's in the EU), in the Elan factory. They feature a sidewall construction, with thicker edges that have bigger teeth for more inset into the ski. Said edges are actually mounted in rubber, so as to dissipate big impacts, like landing on rails. The THalls have sintered bases, and a "jib-specific" flex pattern that is extremely stiff under boot, while softer at the the tip and tail for better butters and olleys. Armada's THall is built to the highest level they possibly can be, quality is super high, and it's basically the best park ski on the market.
The Invader isn't a bad ski at all, but it's simply cheaper. Extruded bases (perhaps slightly more durable, but really just easier to take care of) that are cheaper, cap construction (this isn't a cap vs sidewall debate) that is less expensive to manufacture, and all of it done in China, where manufacturing costs are lower. The milled core does, however, produce a flex pattern similar to that of the THall, and it does have a fully centered stance and sidecut. Overall, a good buy.
The Fujative, also a cap ski, also made in China (the cheaper options), are a soft-ish, cheaply produced ski. I can't comment on the bases, but there's nothing special in them. The edges don't seem particularly thick, and they're not mounted in rubber either. Basically, it's a ski made as cheaply as possible.
THalls are more expensive because most, if not all materials in them are superior, they're made using a more expensive manufacturing method, they're made in a locale where manufacturing is more expensive, and the flex pattern is really, truly as advertised. I recommend you go to your local shop and check all 3 out before making inflammatory posts about Armada's pricing on the THall being off. Or, alternatively, at the very least , knowing something about the skis and manufacturing methods before posting.
They're not all the same. They're not all priced the same. They're not aimed at the same consumers (though they're all park skis, yes.), and they aren't purchased by the same categories of people. Kids who want a cheap park ski that works all mountain get the Fujative, kids who ride nothing but park and don't wanna break the bank get the Invader, and kids who need 2-3 pairs of skis, who are really good, and who want the best, cost be damned, buy the Armadas.
Simple.