SQL & PL/SQL

I run almost same two query one without view , second without view
qury 1 -> select deptno , count(deptno) over (partition by deptno order by deptno ) tes from emp;
qury 2 -> select deptno,tes from(select deptno , count(deptno) over (partition by deptno order by deptno ) tes from emp)
where tes > 3 ;

I checked the explain plan of qry1 it gives Cost 4 Bytes 42 Cardinality 14
qry2 it gives Cost 4 Bytes 364 Cardinality 14

what it means what is this Cost , Bytes, Cardinality . only difference in Bytes is it dangerour..?