A certified ethical hacker is a professional who has received certification from an accredited organization, such as the EC-Council, to demonstrate their knowledge and skills in ethical hacking and penetration testing. Certified ethical hackers are trained to use the same tools and techniques as malicious hackers, but with the permission and under the guidance of the organizations they are testing.
A penetration tester is a professional who specializes in testing the security of systems and applications by simulating cyber attacks and attempting to gain access to the system. Penetration testers may or may not have formal certification, and may have a variety of backgrounds and expertise in different areas of cybersecurity.
Overall, the main difference between a certified ethical hacker and a penetration tester is that the former has received formal certification from an accredited organization, while the latter may have a variety of backgrounds and expertise in different areas of cybersecurity. Both certified ethical hackers and penetration testers use similar tools and techniques to identify and exploit vulnerabilities in systems and applications.