Чем отличается Something от Anything? (Somewhere от Anywhere)

Местоимения something и anything обозначают что–то, что–либо.
Местоимение something употребляется в утвердительных предложениях.
В вопросительных и отрицательных предложениях something меняется на anything.
Утвердительные предложения
There is something on the table.-На столе что–то есть.
There is something new for you.-Есть кое–что новенькое для вас.
There is something to eat.-Там есть что съесть.

Отрицательные предложения-There is not anything important.
Там нет ничего важного.
I cannot do anything for you.-Я не могу ничего для вас сделать.
You mustn't do anything about it.-Вы не должны ничего делать по этому поводу.

Вопросительные предложения
Is there anything on the table?- Есть что–нибудь на столе?
Is there anything new for you?- Для вас есть что–нибудь новенькое?

Somewhere- Anywhere

Somewhere refers to a specific place while anywhere refers to, well, any place. However, it is one of the endearing (or frustrating) traits of English that those two can mean the same thing at the same time. Sometimes.

In The Wizard of Oz, Dorothy sings of "Somewhere over the rainbow," which refers to a specific place of happiness she might someday visit. She is imagining a single location.

Somewhere refers to a specific place while anywhere refers to, well, any place. However, it is one of the endearing (or frustrating) traits of English that those two can mean the same thing at the same time. Sometimes.

In The Wizard of Oz, Dorothy sings of "Somewhere over the rainbow," which refers to a specific place of happiness she might someday visit. She is imagining a single location.

In the song "Anywhere I Go" the neo-ska / permanently stoned band Slightly Stoopid talks about "Anywhere I go I choose to be with you," meaning wherever "I" go, be it Kalamazoo or Djibouti, "I" will choose to be with "you". This could be any location.

something = что-то, anything = что угодно
НО в отрицаниях и вопросах anything = something