While
附件 can be used for physical accessories, `
配件 (pèijiàn)` is often more specific for machine parts, components, or fittings that are essential for or designed for that machine (e.g., spare parts for a car, components for a computer).
附件 is a bit more general, like an add-on that might not be a core component. For a phone, the charger is a
配件, while a decorative phone charm could be seen as an
附件. In many cases, they are interchangeable.