A Guide to YouTube SEO
A landing page should not be your homepage. A web page should be designed for a specific audience. Before designing a web page, a designer/developer needs to ask an important question: What is the objective of the web page?  
A landing page is designed specifically for a campaign. A campaign has a specific goal. A landing page is a web page designed with that specific goal in mind. 
Let’s talk about homepages. Your homepage is the front page of your website. It has a lot of information as as compared to a landing page. When visitors on the web, arrive at your website; not all of them will be looking for the same information. 
Let us tale the example of people visiting my website. When they arrive at my homepage, some of them might be looking for your services, the others might be interested in my contact information while still others might just want to read my blog. They can locate the information they are looking for and follow the desired internal links to visit the pages they need to go to.
Now lets talk about the information on my landing page. The only information my landing page has, is the information about my campaign. It has a clearly displayed CTA (call to action)  button which is the only exit point you can get to after you fill up the information about the offer. 
Example of a landing page with a CTA button.
To summarize, we can say that a landing page only has specific information and also a well laid out plan of action ie. fill out information required for the offer. It also has a prominent, clearly displayed CTA (call to action) button. While a homepage has more information on it, and more exit points (internal links they can follow to reach other pages).