These are absolutely two different methods of promoting sites in search engines in terms of technical work to achieve the result, namely to get your website on the first page of Google.
SEO (Search Engine Optimization) promotion is a process of improving the website from a technical, web design, and informational point of view. Google has an algorithm that analyzes your website and gives it a specific position in the search results. In order for your site to be on the first page of the organic search you need to meet all the latest standards of site building. You can promote a limited number of search queries. The process of improving the website and bringing it to the first positions can take up to 6 months
Google Ads is an advertising cabinet where you can quickly get your website on the first page for a certain advertising budget, but you have to pay directly to Google for each click. The cost per click can vary from $0.10 to several tens of dollars (depending on the type of business and region of promotion whether it is New York, San Francisco, or San Diego). You can promote an unlimited number of search queries. The process of setting up and launching an advertising company takes up to 5 days