This might be just one time observation but minimal installation took more time than the normal installation. Then I looked at the logs while installation, and observed that some software packages like libreoffice,Thunderbird, Transmission ... are being removed. So my question is
Does ubuntu-desktop minimal installation just installs all packages that the normal installation installs and then removes some?
If yes, why? why install them in the first place?
EDIT
Just to be clear:
"Minimal installation" is a new option in the Ubuntu 18.04 Desktop installer, not to be confused with the minimal ISO (see tag "ubuntu-minimal")