efficient
高效的,强调过程省时省力、资源利用率高
effective
有效的,强调能达到预期目标/产生预期结果
The factory's new assembly line is highly efficient, reducing production time by 40%.
工厂新的装配线非常高效,将生产时间缩短了40%。
The vaccination campaign was effective in reducing the spread of the disease.
疫苗接种运动在减少疾病传播方面非常有效。