Customer Status on Orders

Reports: Financial>Order Detail show purchases by Contact Status which can be:

ClubMember
Repeat Customer
1stTimeCustomer

But why are some blank? Can we assume that those are 1st time customers?

The report I am looking at does not show any “prospects”, but I would understand those to be people who sign up for the newsletter who make 1st time purchase, but then they would be come a 1st Time Customer, right?

Thanks