Supply chain (SC) handles more or less regular shipments for regular customers, where CC handles ad hoc shipments.
That's the simple version but ... here is a bit more.
SC handles inventory logistics for production, warehousing, transportation logistics for specialized shipping, and I heard fullfilment services but have not seen that operation. A lot of the Pharma loads for CC come from SC, and some CC trucks sometimes see warehouse services from SC.
Are you thinking about going there?
The last I heard they are not taking on contractors but that was a few months back.