I don't know if the book i've read is correct - but from this and what
i've experimented with i don't quite agree.

For package management one can use apt-get, aptitude, and synaptic.
However, which ever one you use you update INDIVIDUALLY. apt-get upgrade
DOES NOT upgrade synaptic. For synaptic you use RELOAD. For aptitude you
use Actions> Update or just type 'u'.

When adding/removing software aptitude provides some significantly
useful capabilities - but aptitude only remembers dependency info for
packages it has installed. As i've learnt aptitude helps control those
packages that accumulate. It is a ghastly interface but offers more
power if you can spend the time reading the manual. Why don't more use
it - i think the manual puts them off!

I use the apt-get for the command line utility but aptitude for
installing and removing.