Ethical hacking is an extensive term that covers all hacking techniques, and other associated computer attack techniques. So, along with discovering the security flaws and vulnerabilities, and ensuring the security of the target system, it is beyond hacking the system but with a permission in order to safeguard the security for future purpose. Hence, we can that, it is an umbrella term and penetration testing is one of the features of ethical hacking.
Our intuition about the future is linear. But the reality of information technology is exponential, and that makes a profound difference. If I take 30 steps linearly, I get to 30. If I take 30 steps exponentially, I get to a billion.