schema or database

hi, all;

I am new here. And I need some suggestion.

I have many similar database to store data for every customer.
Structure of database is almost the same.
As I use same application to control all these data, so I can only use
one database user to connect to these database.
And I have no needs to query table for different customer together.

I wonder which I should use, different shema or different database to store data?

I 'd like to know the advantage and disadvantage for using schema or database.

Thanks

michael