Alright Tomi !
well for start it ain't hard house but Hard House has borrowed alot from acid techno - no chiken and egg situation here Acid was first - and nowt wrong with a bit of HH especially if you're gay and that.
Well i'm my mind its a few things - 303's help but alot doesn't have 303s like cluster, routemaster, yolk, powertools etc. then it comes down to labels and that rollercoaster banging party sound. For example Lars Klien's Virus EP is very acid techno but some people would shoot you for saying it but Powertools is hard techno, that frankly everybody would agree with (except maybe a few inbreds from scotland [sic])
In the UK acid techno is almost exclusively Truelove or truelove collaborated artists. In the US it has a more old skool feel and very 303 based like Woody McBride/DJ ESP.
But frankly, acid is a happy party attitude that means you ain't sat on a sofa in some shiny shithole in Islington/Clapham paying £4 a pint for every cunt to ignore you, its being battered in a warehouse or a field witha big smile on your face - or is that squat? :)