In Nmap, the difference between -v and -V lies in their functionality. The -v option stands for ‘verbose‘ and is used to increase the verbosity level of the output, providing additional details about the scanning process

-V option is specifically designed for ‘version detection.’ When used, Nmap not only performs regular port scanning but also attempts to determine the version of services running on the open ports. So, in summary, -v makes the scanning process more verbose, while -V focusing on detecting the versions of services.