I was also interested about it and from my research, Fish has two major differences: - it enables the cool functionality out of the box, so unlike zsh you don'

I was also interested about it and from my research, Fish has two major differences: - it enables the cool functionality out of the box, so unlike zsh you don't need to have large configuration file to enable everything - it is not afraid to break bash compatibility to fix confusing scripting issues, so fish most likely will fail when executing a bash script, but writing scripts in fish should be more enjoyable