A positive statement is one that can proved right or wrong by the use of evidence.
For example ‘Volkswagens share price fell by 34%’ or ‘the interest rate in the UK is 0.5%’.
These statements can be supported by evidence and are therefore positive statements.
A Normative statements is one based on opinions.
For example ‘Volkswagens share price is now too low.’ Or ‘The Bank of England should raise the interest rate in the UK.’ These statements cannot be proven. You may use evidence to back them up but they cannot be demonstrated to be true or false.