Applying to PhD programs whose research topics mismatch my experience I am applying to PhD program that matches the theme of my research and industrial experience. As most of field of studies, there are several topics under the general theme and my experiences are just one of them.

If PhD application is all about the relevance between targeted research group and applicant's experience, how to stand out if I am trying to apply to research groups whose ongoing projects (or done ones) are not closely related to my experience (though they might belong to a common general theme)?

To be more specific, let's say my research experience was building a pioneering application built upon several basic tasks as building blocks. On the other hand, the funded projects and main topics of the targeted research groups are focused on improving the basic tasks (efficacy, for example).
It can be an advantage. Many people are aware of the value of interdisciplinary research. Your different background knowledge can bring new views into their field. That is a good card to play.