Absolutely. Thank you for that question.
Efficacy means the vaccine impact in a randomized control trial where you actually choose the population—choosing in the sense that you have very strict inclusion and exclusion criteria. Usually your population is healthier than when you use it in the real world.
Effectiveness is the impact of a vaccine when it's rolled out at the population level, which means that everybody is vaccinated. You have immunosuppressed patients, people with underlying medical conditions and malnourished people who might not respond as well to a vaccine. You always expect the rate of effectiveness to be a little bit lower than the efficacy because you have a much more varied population in whom the vaccine might not work as well as when you select—not cherry-pick, but very strictly select—the participants in a study.