What's the difference between ls and la? Why do they give the same output?

la is an alias to ls -A defined in ~/.bashrc file in Ubuntu.

It only shows the same output if you have no hidden files or directories.

ls -A shows hidden files and directories.

la is defined as an alias in Ubuntus ~/.bashrc file together with a few others. la is simply an ls -A as you can see in the following snippet from the ~/.bashrc

# this alias is defined earlier to grant colored output
alias ls='ls --color=auto'

# some more ls aliases
alias ll='ls -alF'
alias la='ls -A'
alias l='ls -CF'
alias li='ls -lF'

When in doubt, type la.

Bash output:

la is aliased to `ls -la'

Fish output:

la is a function with definition
function la --description 'List contents of directory, including hidden files in directory using long format'
    ls -lah $argv
end