"C-value paradox": There is supposedly a crude direct relationship
between genome size and the complexity of the
organism (I think measured in terms of # of cells
or cell types).
Eukaryote vs Prokaryote: Eukaryotes have their genetic material in a
membrane-bounded subcompartment (the nucleus).
Examples include Animals, Plants, Fungi, Protozoans,
and Slime Moulds.
Prokaryotes (bacteria & "blue-green algae") do
not have a separate nuclear compartment. There
is a major division in the prokaryotes (archeans
vs eubacteria) which is about as ancient as
the divergence from eukaryotes)
There are other distinctions, but most of them
require exceptions and caveats.
Hope it helps.
Department of Cellular and Developmental Biology
Department of Genetics / HHMI
robison at biosun.harvard.edu