Looking for information on villages of Kasimirowka and Sawalowka.

Villages located between Zhitomir and Kiev.

Ship manifest identifies ancestors came from Radomysl, 1902. Was Radomysl a town, village, or area/state in Volynska, Ukraine, Russia.

Could someone please explain the above geographic areas and how they correspond to US terms of city, county, state, country?

Is anyone else researching ancestors from these villages?

Thank you.