This is largely a terminology problem (or an english problem) so to speak. Liver depression is related to Liver Fire and Liver Qi Stagnation. One way to view it as a sort of middle ground between fire (i.e. ascending, problems in the head, etc.) and heat (i.e. more local problems, stronger agitation in the digestion, etc.). So the progession of disease -could- be liver stagnation leads to liver depression (i.e. stagnation generating heat) which may culminate eventually in liver fire (i.e. full ascending heat, problems in the head - dizziness, vertigo, etc.) or may temporarily flare with fire and calm down at times to heat.
Another way to view it might be to say that liver fire is acute and short-term and liver depression (stagnation/heat) is more chronic - but my understanding of the chinese terms is limited.
Herbally it might be read as liver stagnation (xiao yao wan), liver depression (jia wei xiao yao wan), liver fire (long dan xie gan wan) - as examples....
Liver depression appears in Bob Flaw's texts at times and he tends to use terms that are different than those in standard tcm texts (cannot comment at all whether this is good, bad, right or wrong...). So he has:
Liver Depression Qi Stagnation (i.e. qi stagnation)
Liver Depression Spleen Vacuity (i.e. qi stagnation with sp qi def)
Liver Depression Transformative Heat (i.e. qi stagnation with heat signs)
Liver Stomach Depressive Heat and Counterflow (i.e. counterflow qi w/qi stagnation
)There was a discussion on an email list about ten years ago that had it explained as below:
"The full and correct Chinese term for the pattern of liver fire is ascendant
liver fire flaring (gan huo shang yan). The term for liver
depression is either liver depression transforming heat (gan yu hua re) or liver
depression/depressive heat (gan yu, yu re). Fire (huo) is
quantitatively more extreme than heat (re). Because liver fire is shang yan
(ascendant and flaring or flaming), it's symptoms manifest
primarily in the region of the head: headache (as in trigeminal neuralgia), red,
painful eyes, a bitter taste in the mouth, a red facial
complexion. Liver depression/depressive heat's symptoms are not as intense and
are not necessarily located in the head (shang,
upper, above). They include a bitter taste in the mouth, irritability, rib-side
pain, epigastric burning pain, hot, painful nipples, profuse,
bright red-colored menstruation, a shortened menstrual cycle or lengthened
menstrual period, red tongue with yellow fur, and a
bowstring, rapid pulse."