Just to add to what Connor has said:

@ When we can use any query with ''From '' clause, can we call it subquery???

According to Oracle Documentation, we can:

https://docs.oracle.com/database/121/SQLRF/queries001.htm#SQLRF52327

A query is an operation that retrieves data from one or more tables or views. In this reference, a top-level SELECT statement is called a query, and a query nested within another SQL statement is called a subquery.

https://docs.oracle.com/database/121/SQLRF/queries007.htm#SQLRF52357

A subquery in the FROM clause of a SELECT statement is also called an inline view

We can use either subquery or inline-view to name such queries.
The latter is more strict.

WITH
factored_subquery AS -- ANSI SQL-99: "Common Table Expression"
( SELECT 1 AS scalar_value
    FROM DUAL
)
SELECT ( SELECT *
    FROM factored_subquery ) as scalar_subquery
     , scalar_value
  FROM
( SELECT *
    FROM factored_subquery ) /* as */ inline_view;

SCALAR_SUBQUERY SCALAR_VALUE
--------------- ------------
              1            1

https://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:1594885400346999596

see:

with function f return sys_refcursor is
ret sys_refcursor;
begin
   open ret for select * from dual;
   return ret;
end f;
select count(*) from
   (select f() f from dual connect by level <= 10),
   (select f() f from dual connect by level <= 10)
/

  COUNT(*)
----------
       100

but

with function f return sys_refcursor is
ret sys_refcursor;
begin
   open ret for select * from dual;
   return ret;
end f;
iv as (select f() f from dual connect by level <= 10)
select count(*) from
   iv, iv
/
iv as (select f() f from dual connect by level <= 10)
              *
ERROR at line 7:
ORA-02345: cannot create a view with column based on CURSOR operator