barrier
barrier(障碍,强调「阻止进入或通过」:a barrier to entry = 进入壁垒;break down barriers = 打破壁垒)
obstacle
obstacle(障碍,强调「路途中阻碍前进的事物」:an obstacle to progress = 进步的阻碍;常用于比喻路途中的绊脚石)
Cost remains the greatest barrier to the widespread adoption of renewable energy in developing nations.
成本仍然是发展中国家广泛采用可再生能源的最大障碍。
The lengthy approval process proved to be a major obstacle to completing the construction project on schedule.
漫长的审批流程被证明是按时完成建设项目的重大阻碍。