阻拦 (zǔlán) means 'to stop, to obstruct' and focuses on actively preventing someone from moving or acting, often by physical or forceful means. It is stronger and more confrontational than 拦 (lán 'to block, flag down'), which is neutral and can be as simple as raising a hand to stop a car. 阻挡 (zǔdǎng) is similar but emphasizes blocking a path or progress, while 阻碍 (zǔ'ài) is more abstract, like hindering a process.