The simple difference
Google Ads is paid placement. You pay when someone clicks, calls, or interacts depending on the campaign type. SEO is the work of improving your website, Google Business Profile, content, reviews, technical setup, and authority so you earn visibility in organic results and Maps.
Google Ads
Fast to launch, easier to test, useful for urgent campaigns, but visibility usually stops when the budget stops.
SEO
Slower to build, harder to shortcut, but strong pages and Maps visibility can keep producing enquiries over time.
For a local business, the best question is not "which channel is better?" It is "which channel can produce profitable calls, quotes, bookings, or visits at this stage of the business?"