ASO
App Store Optimization also known as ASO or App Store SEO is the process of optimizing a game or application in order to maximize its visibility in the stores in Search (when users search) and Explore (when users browse), increase traffic to listing and improve conversion rate to generate the maximum volume of organic downloads.
ASO = Traffic + Conversion.

This process requires a critical understanding of how the stores work, the target user base, and the most relevant keywords potential users are typing or speaking to find apps or discover new ones

SEO
SEO stands for Search Engine Optimization, which is the practice of increasing the quantity and quality of traffic to your website through
What goes into SEO?

• Quality of traffic. You can attract all the visitors in the world, but if they’re coming to your site because Google tells them you’re a resource for Apple computers when really you’re a farmer selling apples, that is not quality traffic. Instead you want to attract visitors who are genuinely interested in products that you offer
  
  
• Quantity of traffic. Once you have the right people clicking through from those search engine results pages (SERPs), more traffic is better.