Reference sample:  a sample of a batch of   starting material ,   packaging material  or  finished product  which is  stored  for the purpose of being analysed should the need arise during the  shelf life  of the batch concerned. Where stability permits, reference samples from critical intermediate stages (e.g. those requiring analytical testing and release) or  intermediates , that are transported outside of the manufacturer's control, should be kept.

Retention sample: a sample of a fully packaged unit from a batch of finished product. It is stored for identification purposes. For example, presentation, packaging, labelling, patient information leaflet, batch number, expiry date should the need arise during the shelf life of the batch concerned. There may be exceptional circumstances where this requirement can be met without retention of duplicate samples e.g. where small amounts of a batch are packaged for different markets or in the production of very expensive medicinal products.

这里边提到的starting material是指制剂的起始物料就是API的意思，而retention sample只适用于制剂。