The chart below shows the equivalence between the zones in different models. In the three zone (Lactate) model LT1 extends to 80% of HRmax and LT2 to 87% of HRmax. The Norwegian Olympic model splits LT1 and HIT into additional zones but is still based around the idea of Lactate thresholds as is the Coggan model. Coggan defines his 5 zones based on the LT2 heart rate. Garmin calculates the 5 zones using 10% differences in Heart Rate descending to 50% of HRmax. This chart uses an LT2 heart rate of 162bpm and max HR of 186 bpm to calculate the Coggan zones.
If you are using a Garmin computer LT1 comprises zones 1 to 3 and HIT the very top of zone 4 into zone 5. LT2 is actually quite a narrow range of heart rates. The Lactate model can be simplified into a binary model by combining LT2 and HIT into a single HIT zone.