AS ABAP only or ABAP AS+JAVA AS

Dear Experts,

Our whole solution landscape include ECC 6.0 and BW 7.0. my question is do we need to have AS ABAP + AS Java on ECC 6.0 are AS ABAP enough for our landscape.

Please tell me what will happen if we donot install AS Java on ECC 6.0.

and the core pupose of having AS ABAP + AS JAVA.

please revert back if u donot understad my words i will explain them again..

Thanks