Technically, are shelf life and expiration date the same or different?

Technically, are shelf life and expiration date the same or different?

Technically, Shelf life and Expiration date meaning is the same.
However, there is a difference between the Expiration date and the Retest date.
The retest date can be extended further if the stability sample’s analytical results are within specification when analyzed at the retest date. However, the Expiration date can not be extended further to increase the shelf life.
Generally, the terms ’ Shelf life and Expiration date’ are used for pharmaceutical finished products (Drug products) and the term ‘Retest date’ is used for APIs (Drug substances).