I wouldn't say they ALL are -- but I'm sure that at least some of any given model line come from the same factory in China or Taiwan. Doesn't guarantee parts are interchangeable ... but it does mean that, for reasonably similar cheapo Chinese tools, you should buy based on price point and not brand.
The great thing about HF is that their regular prices are okay, but if you don't absolutely need the item today, watch for it to go on sale, generally at two-thirds or half it usual price.
Alternately, you can buy a nicer tool on sale for what you would have spent on the cheap one.
HF, like JC Whitney, usually has a REALLY cheap item in any given category (like the $20 sawzall), then one that's considerably more (say, $40 for this case) and another that's a bit more than that (say, $50.)
The $20 one is junk. Either of the $40 or $50 items would prolly work. But the $50 one on sale for $25, now we're talking
Just my .02 on such things.
-- A