The difference, when there is one, is about being polite:

Would you like some milk in your tea? [a Polite way to ask the question]

If you know the person and the person is your friend, you can say:

Do you want milk in your tea?

It really is as simple as that.

Do you want us to have lunch in that restaurant? But normally one would say: Do you want to have lunch there? BUT: Do you want him to leave school early?

The difference, when there is one, is about being polite:

Would you like some milk in your tea? [a polite way to ask the question]

If you know the person and the person is your friend, you can say:

Do you want milk in your tea?

It really is as simple as that.

Please note the grammar point below: Do you want we have the meeting in this room?" "Do you want we have lunch in that restaurant?"= To be grammatical, those need to be changed to:

"Do you want us to have the meeting in this room?"

"Do you want us to have lunch in that restaurant?"

Please note: to want [someone] to do something is one expression.
Another is: Do you want x? Do you want lunch now?

The difference, when there is one, is about being polite:

Would you like some milk in your tea? [a Polite way to ask the question]

If you know the person and the person is your friend, you can say:

Do you want milk in your tea?

It really is as simple as that.

Do you want us to have lunch in that restaurant? But normally one would say: Do you want to have lunch there? BUT: Do you want him to leave school early?

To want somebody to do something is not to want something.

The difference, when there is one, is about being polite:

Would you like some milk in your tea? [a Polite way to ask the question]

If you know the person and the person is your friend, you can say:

Do you want milk in your tea?

It really is as simple as that.

Do you want us to have lunch in that restaurant? But normally one would say: Do you want to have lunch there? BUT: Do you want him to leave school early?