No, hippeastrum is actually the correct term to refer to them.
Amaryllis is a fixed name for the trade, hence the common name for general population.
This plant has a hollow flower stalk, but I don't think that is the way to tell what is what.
Amaryllis is a name that covers lots of plants as I understand it in technical manner, but when I see a flower like above, I just call them Amaryllis even though I know the correct name is Hippeastrum.
I doubt people will understand what I mean if I called them hippeastrum, wherease the term amaryllis will instantly help people know What it is.