Hello Dr. Burhanuddin,
I think a preliminary questions is whether the vocative requires, as a rule, any of the normal three cases in Arabic? If there is such a rule, then this constitutes a difference. This is because English nouns (except pronouns) never have any case, regardless of being vocative or not.

Another difference is the frequency with which a vocative particle is used. In poetic or dramatic English, O can be used (e.g. O great king!), but this almost never occurs in spoken English. However, I understand that the particle yaa is used in both written and spoken Arabic.

What are your thoughts, Doctor?

• Clay Bahl