WHO distinguishes between vaccine efficacy and effectiveness

The WHO publishes an information webpage that explains the difference between “vaccine efficacy, effectiveness and protection.”

According to them vaccine “efficacy” has to do with clinical trial results and vaccine “effectiveness” can only be determined after the vaccine is used in the population, and vaccine level of “protection” has to do with the time period following the injection, protection takes time to build.

So if clinical trials determine “efficacy” why do they refer to it as 90% effective, if effectiveness is determined by “how the vaccine performs in the wider population”?