While both are tools for web application security testing, they are very different in origin and capabilities. Invicti offers a dedicated and mature DAST-based platform (also including IAST and dynamic SCA) for automated vulnerability scanning in production and integrated testing during development. Qualys WAS is a more basic cloud scanner typically offered in combination with Qualys’s main products from the Qualys Cloud Platform.
Read more about building DAST into the software development lifecycle