Trojans and viruses (or virii) are both malware, but are defined differently, and the difference is critical.
Both definitions hearken back to their namesakes — Trojans, named after the Trojan Horse story from mythology, are legitimate-looking programs that entice the target to install them, while containing a hidden “payload” of benefit to the attacker. They are purely social engineering attacks.
Viruses (named after the microscopic organisms), “infect” systems and spread to other systems. These typically exploit operating system or application vulnerabilities to infect and propagate.
Back to my oroginal point. Viruses, trojans and worms need to know names of folders and your OS structure to be effective. I don’t wish anybody to have them. Just sayin’, your aren’t impervious to attack if someone chooses to attack you like they did(and do)PCs.