Malware is abbreviation of malicious software which is basically a software developed by cyber criminals to run on user’s systems (PC or any device) and gather internal information or damage or make harm to the system or applications.
This software is considered as Malware because of the perceived intent of the software. Malware includes Viruses, Worms, and Trojan horses, Spyware, Adware, Scareware and Crimeware.
Virus is also a software program which we can define as a subset of Malware. There are different types of virus programs exist but generally virus programs are placed or attached to commonly used program so that virus programs will be activated when commonly used programs are started. These commonly used programs could be applications installed in your computer or attached to operating system files.
Mostly viruses spread via email attachments and some of them spread via floppy disks, DVD, CD, External Hard Drive or USB storage drives.
On top of the above mentioned media, viruses can easily spread to other computers by infecting a file on network file system or commonly used file placed in a storage network.
Normally viruses are not self propagating where as worm is also a Malware which is self propagating.
Summary:
(1) Malware is software which may harm or steel information on your systems. (PC)
(2) Virus is subset of Malware.
(3) Viruses are not self propagating.
(4) Viruses placed with or attached to a day today applications or application files so when it starts viruses also get activated.
(5) To prevent from viruses, you can install any Antivirus software and update it and scan your system frequently or as per scheduled.
(6) Better to scan all storage devices (Portable HDD, DVD, CD, Floppy, USD Storage) when you connect them to your System (PC) before using the files on those devices.
(7) Mainly use your antivirus software to scan all you email especially all incoming emails.
(8) To prevent from viruses, do not click unwanted links or download unwanted software from internet and install them on your system.