Threat
A potential danger or harmful event that could exploit a vulnerability and causes harm to the system. It could be both accidental and intentional.
Vulnerability
A weakness or flaw in the system using which a threat actor could perform malicious activities against the system.
Risk
likelyhood of a vulnerability getting exploited in the system.
Exploit
series of steps that should be followed to take advantage of a vulnerability in the system to achieve unintentional and harmful outcomes on the system.