You can check the features available in each version of Avast Antivirus on our product comparison chart.
Avast Free Antivirus: includes our intelligent antivirus features that detect viruses, malware, spyware, ransomware, phishing, and other threats in real-time. Avast Free Antivirus also includes Software Updater, Ransomware Shield, and core Firewall functionality.
Avast Premium Security: comes with all the features included in Avast Free Antivirus, and additionally includes Real Site, Sandbox, Remote Access Shield, Sensitive Data Shield, Webcam Shield, Password Protection, Data Shredder, and advanced Firewall features.
Avast Premium Security (Multi-Device): comes with all the features included in Avast Premium Security, and additionally includes Avast Premium Security solutions for Mac, Android, and iOS.
NOTE: Avast SecureLine VPN and Avast Cleanup Premium appear in the Avast Premium Security product but require separate, paid subscriptions.