Technically when we say homepage, we actually mean the first page you see on your website. When we say your landing page, it’s actually refering to your other main pages or the top page of every sub-category/level.
For instance, if I had a button called Categories and when you click on it or place your mouse cursor over it, it drops down several other options. The Categories link when clicked on brings you to your landing page for that parent link.
Some people don’t have a landing page for their parent link because it doesn’t benefit their website. However, when some people do use their landing pages, some don’t use it beneficially.