What is the difference between blocking and filtering?
sites are filtered based on content; sites are blocked based on words or phrases.
sites are filtered based on words or phrases; sites are blocked based on content. filtering is for sites that may or may not be harmful; blocking is for sites that are always harmful.
filtering is for sites that are always harmful; blocking is for sites that may or may not be harmful.

Sites are filtered based on words or phrases; sites are blocked based on content

Explanation:

Filtering:-  this job is done by antivirus which is installed on a desktop   or laptop or workstation.  Filtering works on word phases.  Moreover in the digital world antivirus automatically cross the internet and make sure it filters website content and words, not show to end-users.

Blocking:-   antivirus which is installed on a desktop or laptop or workstation check the website whether any harmful active object is downloaded such Trojan virus and make sure the end-users are blocked  not access the website.  moreover it safer to end-user where his or her desktop or laptop or workstation is not affected by the virus.

answer; the correct answer is (operating system);