No they're not
A Galaxy S looks like the twin brother of an iPhone 3G(s). Albeit a large and thin brother.
Compared to an iPhone 4 there's a very noticable difference.
Many websites in their review also suggested the same e.g.:
"The glossy black plastic and metal-effect bezel both echo Apple’s second/third-gen smartphone; the irony, of course, is that the Cupertino company has now moved on with the almost retro lines of the iPhone 4, and the Galaxy S feels a little indistinct in comparison." (source: slashgear.com)
And there are a lot more who suggest the same (another example from s Dutch website: "Opvallend is dat iedereen die de telefoon voor het eerst in zijn handen krijgt vrijwel meteen zegt: “Goh, het lijkt wel erg op een iPhone”. --> translated as: "Everybody who gets the phone in their hands say: "Gee, this looks a lot like an iPhone") (source: androidplanet.nl)
And just look at: http://www.gsmarena.com/samsung_i9000_galaxy_s-review-478p2.php#
The 2 top photo's show the galaxy next to an iPhone 3GS. Even the UI resembles iOS screen filled with icons and a grey bottombar with its 4 icons.
You gotta be blind NOT to see the iPhone resemblance. Remove the 2 imprints next to the bottom button and the samsung logo on top and you'd swear it was a bigger iPhone 3.