As I was looking for some tips specific for workplace learning I came across this article:

A tip on how to remember the distinction between the two:

Formative = “…‘formative informs”.  The idea is that I am informed about how the trainee is performing at various stages of the training….The aim of formative assessment is to improve the amount of learning that occurs.”

Summative = “…summative is a summary”.  The idea is that it summarises how the trainee has performed at the end of the training….The aim of summative assessment is to prove that learning has occurred.”