Technical SEO is focused on the technical aspects that make up the back and front end of a website, such as the code, structure, and architecture. It looks at how search engine bots crawl and index a website, and how to optimise towards that. This includes optimising HTML tags, improving website speed and performance and ensuring the website is mobile-friendly.
Regular SEO, on the other hand, is focused on increasing the visibility of a website in organic search engine results. It involves analysing and improving the content of a website, as well as optimising external factors such as link building. Regular SEO also looks at how to optimise the user experience, such as improving page layout and navigation, as well as using techniques such as keyword research to target the right audience.