Linking a local vue.js to my html: two links; both can reach the file, but only one can read the Vue

Question

<script src="./lib/vue.js"></script>
<script src="../day01/lib/vue.js"></script>

You can see two links, both can head to the file in my computer, but the first can read Vue, the other can not.

second one will show bugs like the picture below

First one can show the result normally. what's the difference between them?