To the untrained eye, many siberians indeed look like regular old domestic medium and long hair tabby cats, however, the odds that one came walking up to your house or you found one in a shelter are close to zero. Tons of cats on petfinder are listed as siberians, and they are really not. They just call them that way because that way they adopt out faster if they claim it's a purebred "hypoallergenic" cat.
The siberian breed has only been in the USA since 1994, and have only been in the show halls for 15 years. The odds you find them on the street or in a rescue are close to nothing. There is a pure breed siberian rescue and other then sometimes a breeder getting out of the business will get some siberians in rescue but that rarely happens.
It is not possible to determine whether a cat is a siberian based on pictures. You need to have the cat in your hands, feel the coat, feel the body shape and built that is very specific to a siberian. And even then there is no telling if it is actually a purebred siberian. I know people badly want their stray or shelter cat to be a siberian, but the chances that your beautiful kitty is an actual siberian, is close to nothing.
The kitten on the picture is looking an awful lot like a siberian kitten, right? It's not. This is our Oliver that was a stray kitten and he is a beautiful cat but not a siberian.