pedicate - left or right side

[stmontgo]

Is this ultra simple stuff or am I missing the banana boat yet again..

why is

SELECT company.DESCR, 
       company.DESCRSHORT 
  FROM PS_company_TBL COMPANY 
 WHERE :1 = company.company 
   AND company.EFFDT = (SELECT MAX(C2.EFFDT) 
                          FROM PS_COMPANY_TBL C2 
                         WHERE :1 = C2.COMPANY 
                           AND C2.EFFDT <= SYSDATE) 

different than this

SELECT company.DESCR, 
       company.DESCRSHORT 
  FROM PS_company_TBL COMPANY 
 WHERE company.company = :1 
   AND company.EFFDT = (SELECT MAX(C2.EFFDT) 
                          FROM PS_COMPANY_TBL C2 
                         WHERE C2.COMPANY = COMPANY.COMPANY 
                           AND C2.EFFDT <= SYSDATE) 

specifically why is the top one cost 2 and the bottom one cost of 12 when essentially all I have done is put the bind variable on the right in the bottom statement