I was curious so I studied them briefly. Please take it with a grain of salt.
ShellGPT offers a lot of flexibility with outputs(comments, code snippets, and documentation besides shell commands), operating modes (chat mode or REPL), model choice (supports locally hosted models like LocalAI), and custom roles. Clipea, on the other hand, is a simple tool for generating shell commands and has zsh shell integration.
They essentially perform the same task, but the choice depends on your needs.
How about a digital garden post about digital gardens:?