Would like just a Visa for Shenzhen is this same as what is discussed above or something different?

The difference between China visa and Shenzhen visa:
If you hold China visa, you can visit any city in Mainland China including Shenzhen. (Tibet is an exception, besides valid China visa, the Tibet Entry Permit is also required).

If you only visit Shenzhen for 5 days at most, it is possible for you to get a Shenzhen visa on arrival, you can only visit Shenzhen, you can't hold it to visit other cities. It is issued by the entry port of Shenzhen, Luohu, Shekou, Huanggang.