For Example:
create type emp_address as object
(state varchar2(10), zip number(6));

create type emp_address_vrr as varray(4) of emp_address ;

create type emp_address_nest is table of emp_address ;

create table emp (emp_name varchar2(30),
address1 emp_address_vrr ,
address2 emp_address_nest )
NESTED TABLE address2 STORE AS address;

If you know maximum how many address u can insert for one emp_name then go for varray, but if you don't know the number then go for nested table.