"No, it actually seals, but not THAT strong"
I'm sorry, but I fail to see what the point is that you're trying to make. One minute, you're saying it's good for carpets and hard floors because it seals to them, and the next you're saying it's not so good for hardfloors because it seals to them?
You're also saying that the thing that makes it good is the sealed suction at the cleaner head, but then you've said above that "the seal isn't that strong"?
"which shows how better it is on carpets, compared to the others"
Compared to what, Tayyab? What other cleaners are you comparing this against? Other Dyson's, other modern bagless vacuums, a vintage Hoover...what?
Like many Dyson fans, you're saying that more suction = better performance and that's not always the case. I'd much rather have a 250w low suction Hoover Junior with a nice brushroll and beaters to clean a carpet than a high suction Dyson with a crappy brushroll but plenty of suction. If I wanted suction, I'd buy a cylinder.
You're making out here that this DC14 is the greatest thing ever to clean a carpet with, but yet you're not actually backing this up with anything and your limited experience is working against you.