Free antivirus software is behaving same like a paid version?

I have noticed when downloading a free antivirus software, it has major differences in the features such as added extras, VPN, parental control etc compare to a paid version. But when I need only the anti-virus protection we don't need to choose a paid version at all. Do you think free anti-virus software provides the same virus detection and give protection as same as paid one does? What are the major differences between free and paid?