Select count(total ms1) MS1 from A where launch_date = trunc(sysdate)
union all
Select count(total ms2)) MS2 from A where launch_date = trunc(sysdate -1)

I want out put like

MS1     MS2   Diff with (MS1 - MS2)
1000    400   600

select ms1, ms2, 100*(ms1-ms2)/ms2 "%diff"
from ( <your query> ) 
/

with t as (
           select  case
                     when abs((count(*) - lead(count(*)) over(order by launch_date desc)) / count(*)) > .95 then 'alert'
                   end alert
             from  A
             where launch_date in (trunc(sysdate),trunc(sysdate - 1))
             group by launch_date
          )
select  alert
  from  t
  where alert is not null
/

SQL> with a as (
  2              select  trunc(sysdate) launch_date
  3                from  dual
  4                connect by level <= 5
  5             union all
  6              select  trunc(sysdate - 1) launch_date
  7                from  dual
  8                connect by level <= 7
  9            ),
 10       t as (
 11             select  case
 12                       when abs((count(*) - lead(count(*)) over(order by launch_date desc)) / count(*)) > .95 then 'alert'
 13                     end alert
 14               from  A
 15               where launch_date in (trunc(sysdate),trunc(sysdate - 1))
 16               group by launch_date
 17            )
 18  select  alert
 19    from  t
 20    where alert is not null
 21  /

no rows selected

SQL> with a as (
  2              select  trunc(sysdate) launch_date
  3                from  dual
  4                connect by level <= 5
  5             union all
  6              select  trunc(sysdate - 1) launch_date
  7                from  dual
  8                connect by level <= 10
  9            ),
 10       t as (
 11             select  case
 12                       when abs((count(*) - lead(count(*)) over(order by launch_date desc)) / count(*)) > .95 then 'alert'
 13                     end alert
 14               from  A
 15               where launch_date in (trunc(sysdate),trunc(sysdate - 1))
 16               group by launch_date
 17            )
 18  select  alert
 19    from  t
 20    where alert is not null
 21  /

ALERT
-----
alert

SQL> 

ID   MS1     MS2   Diff with (MS1 - MS2)   Percent of Diff   Action
01   1000    400      600     

create table Diff(id number(4),
                  ms number(6),
                  date Date);

Insert into Diff(id , ms, date)
            value(01, 10002, 'sysdate');

Insert into Diff(id , ms, date)
            value(02, 10003, 'sysdate');

Insert into Diff(id , ms, date)
            value(03, 10004, 'sysdate');

Insert into Diff(id , ms, date)
            value(04, 10005, 'sysdate');



Insert into Diff(id , ms, date)
            value(01, 10000, 'sysdate-1');
Insert into Diff(id , ms, date)
            value(02, 10001, 'sysdate-1');
Insert into Diff(id , ms, date)
            value(03, 10002, 'sysdate-1');
Insert into Diff(id , ms, date)
            value(04, 10000, 'sysdate-1');


Insert into Diff(id , ms, date)
            value(01, 10003, 'sysdate-2');
Insert into Diff(id , ms, date)
            value(02, 10004, 'sysdate-2');
Insert into Diff(id , ms, date)
            value(03, 10005, 'sysdate-2');
Insert into Diff(id , ms, date)
            value(04, 10006, 'sysdate-2');

ID   ms of sysdate     ms of sysdate-1      Diff. of ms between two date   Percent of Diff. in two date   


likewise 

ID     ms of sysdate     ms of sysdate-2      Diff. of ms between two date   Percent of Diff. in two date
or
ID     ms of sysdate     ms of sysdate-3      Diff. of ms between two date   Percent of Diff. in two date
or
ID     ms of sysdate     ms of sysdate-4      Diff. of ms between two date   Percent of Diff. in two date

ID   ms of sysdate     ms of sysdate-1      Diff. of ms between two date   Percent of Diff. in two date 
01     1001                1000                 1                                  %.1

ID   ms of sysdate     ms of sysdate-2      Diff. of ms between two date   Percent of Diff. in two date 
01     1002                1000                 2                                  %.2

SQL> create table Diff(id number(4),
  2                    ms number(6),
  3                    date Date);
                  date Date)
                  *
ERROR at line 3:
ORA-00904: : invalid identifier