Great answer from @Tony McCreath.

Hey Danny Wave, there are two separate aspects of your question.

Let's discuss both:

Q 1. What is the Correct Format for Schema Property Types i.e. full URL or just Value wording?

Answer: For Property Types, it's always just value, as you asked, Brand without website url; https://schema.org/. No need to be confused for this as it's crystal clear.

Q 2. What is the Correct Format for Schema Property Values where Schema.org website recommends full URL as Value, like the folllwing:

• For a New Condition of a Product: https://schema.org/NewCondition
• For a Product's Availability in Stock: https://schema.org/InStock

Answer: Google clearly recommends that you can just write NewCondition, InStock also. According to Google guidelines, either you write full URL like this https://schema.org/NewCondition, or you write InStock only, both are acceptable.

Check the below screenshot: ItemAvailability Value Recommendation from Google

Read Google's Recommendation here: https://developers.google.com/search/docs/appearance/structured-data/merchant-listing#availability