We commonly say "we feel depressed" is a temporary state of sadness that appears when we feel sad after loosing a person we love or our job, etc and it is related to a feeling of loss or frustration.
A depressive upheaval is an illness that requires a treatment and that doesn't always have to do with what is happening to us in the present. From a temporary state to a permanent state, where happiness, desire and love's capacity start to decrease and instead appears a feeling of despair and pain, sadness, hopelessness that makes us particularly miserable.