Unfortunately due to the nature of the DSM 5, PTSD is only defined in one way. In Europe however they use the WHO's ICD, which increases the range of PTSD.
Correct, and incorrect. WHO is used globally, even in USA, Australia, etc. DSM is an American manual, yes. It is used in USA, Australia, etc. Many countries use both manuals, and both manuals cross reference one another. In some instances, one manual is used, and others, the other. Why? Because both bring certain things to the table much better than the other.
Talking PTSD, CPTSD. The ICD 11 is now just released, officially. CPTSD has only just, as such with its release, become an official diagnosis. That diagnosis can now be utilised globally, even in America, as there is now a diagnostic code. It is only whether an insurance company, if used and applicable to a treatment for a person, is involved as to which manual may be accepted exclusively. Most insurance companies have both standards for this reason, as between the two texts, some things are covered in one and not in the other.
The ICD 11 PTSD diagnosis now makes PTSD diagnosis harder, not easier or wider scope, than the DSM 5. You think the other... you are incorrect based on all the expert data and comments made available by the groups responsible for the diagnostic outcomes. As PTSD has become trendier in society, the experts are making it tighter to restrict it from criterion creep via interpretation from treating physicians.
ICD 11 PTSD:
ICD-11 - Mortality and Morbidity Statistics
ICD 11 CPTSD:
ICD-11 - Mortality and Morbidity Statistics
You can only be diagnosed with one, not both. With each release we will also see more specific and relevant classification of traumatic events that are causing said conflicts with PTSD diagnosis, such as:
prolonged grief disorder (death). The APA (DSM group) are looking at similar things with future versions too, trying to stop creep into PTSD with emotional trauma that is considered "normal" as part of life events, which is an exclusion for PTSD, yet physicians are stepping around and discarding in labelling patients incorrectly. Back to trendy!
It is not simple. It is ever-changing. Mental health diagnosis is super subjective. Mental health diagnosis really is best guess for the diagnosing physician based on experience, knowledge and personal experiences and bias.