What is the difference between apt-install and in-target apt-get install?

The ubuntu help on preseeding links to an example file which contains this:

# This command is run just before the install finishes, but when there is
# still a usable /target directory. You can chroot to /target and use it
# directly, or use the apt-install and in-target commands to easily install
# packages and run commands in the target system.
#d-i preseed/late_command string apt-install zsh; in-target chsh -s /bin/zsh

Is there a difference between using apt-install zsh and in-target apt-get install zsh?