网址中的http:// domain / path和http:// domain / path /有什么区别

I served a react page under 127.0.0.1/react/ sub directary with my gateway. It can be viewed by explorer with 127.0.0.1/react/. But if I input 127.0.0.1/react it returns my vue page served under 127.0.0.1 which failed to match any routes. There is another example https://www.curseforge.com/minecraft/mc-mods. https://www.curseforge.com/minecraft/mc-mods is okay while https://www.curseforge.com/minecraft/mc-mods/ returns 404 not found. What's the difference? Ordinary users might treat them as same url, they would expect both of them can access the page. So how should I make them both accessable?