Query plan and execution time varies with different decode values

Hi All,

Query plan and execution time varies  between Decode "1" and "2" used in the query.

Attaching the plans for both the queries where one of them gets completed in 10 mins when decode 1 is used and other takes about 40 mins to complete when decode "2" is used in the query.,i know this is bit abstruse to read,still  requesting if anyone has any idea in solving this,

Thank you in advance.

SELECT A.BUSINESS_UNIT,

         A.PROJECT_ID,

         L.DESCR,

         A.ACTIVITY_TYPE,

         A.PROJECT_MANAGER,

         B.NAME,

         A.TEAM_MEMBER,

         C.NAME,

         A.RESOURCE_TYPE,

         A.RESOURCE_CATEGORY,

         M.DESCR,