The gap means that the styles will apply to all nested elements
and ">" means that the styles will apply only to the immediate child element.
For example:
<div class="family">
<div class="parent">
<div class="child"></div>
</div>
</div>
.family{width:300px; height:300px; background:red;}
.parent{width:200px; height:200px; background:purple;}
.child{width:100px; height:100px; background:green;}
If you set the style
.family div{border: 2px solid black;}then, the stroke will appear at all invested in .family divas.
If ask
.family>div{border: 2px solid black;}then, the stroke appears only on the unit .parent