Withdrawal and discontinuation syndrome are synonyms. The later term was coined by the pharmaceutical industry in order to distance SSRIs from opioids in the minds of doctors and patients.
You can taper off of heroin and you can taper off of an SSRI but if you stop either cold turkey, you are going into withdrawal.
The common word for a substance that does this is that it is addictive. When a person says heroin is addictive they are referring to the fact that it produces physical withdrawal when you stop it.
Heroin is also habit forming, SSRIs are not habit forming as they do not create psychological reinforcement through dopamine pathways. So, they do not create a psychological addiction or habit, but they remain physically addictive and your body will still suffer from withdrawal when you quit.
When someone quits coffee we say they have caffeine withdrawals. When someone quits SSRIs we say they have discontinuation syndrome?
It's corporate marketing meant to minimize risks in the minds of doctors and patients. We already had a word for it.
Hence, there's a lot of informed consent issues with psychiatric medication in general but especially SSRIs.
The reason I mentioned it is because the efficacy isn't there especially with stuff like CPTSD and PTSD. So, you give a patient an antidepressant and you diagnose them with depression so the insurance will pay for it, when the underlying cause is actually childhood trauma and then they get a false hope that the depression medication is going to fix them. And they get misdiagnosed in the process.
All of this is problematic for a number of reasons. And of course if the medication doesn't work the doctor will just say well let's try a different SSRI because often we need to go through three or four of them before we find something that works.
What works best for CPTSD is trauma-informed therapy. Thankfully the medical community seems to be getting wiser. And listening to patients better, at least around here.