The difference is at 25000ft ....
An operator shall not operate a pressurized aeroplane, above 25 000 ft,
when a cabin crew member is required to be carried, unless it is equipped with a
supply of undiluted oxygen for passengers who, for physiological reasons, might
require oxygen following a cabin depressurization.... for 2% of passengers...
Oxygen masks for use by flight crew members in pressurized aeroplanes
operating at pressure altitudes above 25 000ft, shall be a quick donning type
of mask.