General sibling means the element is after another element, where the child selector targets elements that are directly inside of certain elements.
Siblings:
HTML:
<div class="brother"></div>
<div class="sister"></div>
CSS:
.brother ~ .sister {
/* This styles .sister elements that follow .brother elements */
}
Children:
HTML
<div class="parent">
<div class="child">
<div class="child"></div>
</div>
</div>
CSS:
.parent > .child{
/* This styles .child element that is the direct child of the parent element;
It will not style the .child element that is the child of .child */
}