Distributions are based on the Linux Kernel. Different for given the services i.e. servers, phones, computers etc.
Examples: Ubuntu, Fedora, CentOS, Debian, Red Hat Enterprise, Arch Linux. Security Specific: Parrot OS, Raspberry Pi OS, Debian, BackBox, BlackArch.
Debian Widely used for stability and reliability. Uses the Advanced Package Tool (apt) package for packet management and security. Higher learning curve, but more flexible and customizable.
Parrot OS Specific version of the Debian Linux system that is focused on security. Has several build-in tools like Metasploit, Nmap, Fluxion, Tor etc.