Glossary
MES vs ERP
Manufacturing Execution System vs Enterprise Resource Planning
Two layers of software that are often confused: the ERP plans and accounts for the business, the MES runs and records what happens on the shop floor.
The distinction is formalised in the ISA-95 model, which stacks industrial systems in levels. Level 4 is business planning and logistics - orders, purchasing, stock, invoicing, accounting - and that is the ERP. Level 3 is manufacturing operations management - dispatching work to stations, recording what was done, tracking units through the process - and that is the MES.
In practice the boundary moves with the industry. Process plants usually run a distinct MES because the shop floor generates data at a rhythm no business system is built to absorb. Assembly and repair operations more often extend the ERP downward, because the unit of work is a serialised item that the business layer already needs to know about.
The question worth asking is not which acronym you need, but where the device record lives. If the shop floor writes to one system and the business reads from another, the two will diverge, and reconciling them becomes a job.
Refurbishment complicates the picture because it inverts the usual flow. A factory consumes known parts to produce known products; a repair operation receives unknown items, discovers what they are, and produces a mix of resold devices, harvested parts and waste streams. Standard manufacturing modules assume the first shape.