Under the Data Protection Act typically PII has been your name, address, NI number etc.
GDPR recognises your data in a much broader term, PII covers any data which can identify a Natural person i.e Name, ID Number, IP address, Biometric data. This is all classed as Personal Identifiable Information
Data which identifies a corporate entity i.e. a companies head office address or company registration is not PII and doesn’t fall under GDPR.