Variants are new strains of malware that are modifications of a previous malware. Today’s cybercriminals continually modify malware in order to get as much mileage as possible from it.
Vishing refers to phishing attacks that involve the use of voice calls, using either conventional phone systems or Voice over Internet Procotol (VoIP) systems.
A vulnerability is a weakness in a system or device that can be exploited to allow unauthorized access, elevation of privileges or denial of service. A tool used to attack a vulnerability is called an exploit.