Although both are technically called audits, they are two very different things. You might run a software-audit using tools like SEMRush, AHREFs, Moz or other SEO tools to stay on top of the changes being made to your site. They are great for, for example, checking for duplicate heading tags, whether you have SSL installed properly and if there are any blatant errors when it comes to crawlability or the schema on your page. Those performed by an experienced SEO audit expert, however, cover a wide range of factors not covered by auto-generated audits and go into far more detail on each of them. They will also go into detail on the best next steps to take and can therefore form the basis of an SEO campaign. For example, an SEO tool might tell you you’ve “failed” your page-speed test, indicating you might need to work on it. A professional audit will detail, among other things, which speed metrics you should be optimizing for based on your user’s behavior on your site, your competitors, and the metrics most likely to improve your search engine performance.