The TMP Klingons had that identical spinal single-ridge look that has never quite been repeated, along with that funky upswept coiffure. TSFS made the forehead ridges more plate-like. Klingons on TNG and DS9 had a more elaborate version of that look, with thicker forehead makeup as well as nose pieces. The half-Klingons in the TNG era and beyond looked like the full Klingons in the TOS movies. Cf that ridiculous Voyager episode "Prophecy" where the Klingon recognizes that B'Elanna is not full Klingon because of her ridges, even though she looks as Klingon as Valkris or Vixis, and even more so than Azetbur!
Kor
Kor