If according to both ACOG and WHO latent phase is till 5cm

If according to both ACOG and WHO latent phase is till 5cm then how come active phase has a different starting point in both of them? One is more than equal to 6cm and the other has more than equal to 5cm

For partogram : active phase starts at 4cm

For rest all practical purposes go with 6cm

I think mam mistakenly said it… In edition 6 she has taught that latent and active phase is upto 6cm and >=6cm in acog, upto 5cm and >=5cm in who, upto 4cm and >=4cm in who partogram respectively