Different between work center and machine center in this case proplem

Hi guys I have specified case proplem

I work in concrete readymix company have more branches.

my purpose from company produce ready mix concrete.

every company have more batch plant

you input gravel and cement and water and sand  to every batch planet as input  and output or result ready mix concrete.

My question here what i must added in machine center and what must added in work center

Example

Company A

Batch pant 1       Batch plant 2

                    car                                                              input                                   output                                             pump car

Supplier-----------------Sand - Gravel -Cement-Water------------------Batch Plant 1--------------------Readymix concrete------------------Customer

Customer sell ready mix

Which here represent work center and which represent machine center

Thanks