What are the differences between Complex PTSD and GAD?
C-PTSD actually requires a lot of work to properly diagnose, whereas GAD tends to be "Anxiety: The Condition", which allows a clinician to diagnose in an insurance company and report friendly way. It can help a person start their journey but is a shallow diagnosis.
Generally C-PTSD is a plethora of things -- internal fragmentation (~1 in 12 or so people are diagnosably plural afaik from the studies I found [i.e. osdd, which no one seems to really know about, to did], though most plurals will never find out about their plurality as it is exceptionally stealthy. Also it's a spectrum meant to hide itself from the brain's "user", as it were, so the subtlety of spectrum disorders adds to the mix), difficulty in relationships (it is in the trifecta of "social stuff trouble conditions" of ADHD, autism, and, well, cPTSD), generally at least occasionally unstable emotional state (which can be entirely internal) which oftentimes is hypersensitive to environmental triggers, and a need for control of relationships and environment (not necessarily evil top hat villain manipulation, this can even be just using a fawn trauma response in constantly giving up self to an extraordinary amount to keep the peace, keep relationships, etc).
Everything seems to be on a co-spectrum, cPTSD is just a map marker for a family I'd contest. It has a ton of overlaps with BPD, for example. cPTSD is differentiated from DID in that the different parts of the brain in cPTSD are not considered especially distinct, but there's also some tricky DID business people's brains can play to stuff certain nearly independent parts of a person away so they'd look more like a low-level cPTSD kind of automatic trauma triggered/autonomic response, etc.
I'm not a clinician, etc, etc, hope that helps from a technical perspective some. Feel free to ask any questions you might have. :)