Scientists who study the structural similarities and differences between organisms are called anatomists.

Here's why:

* Anatomy is the branch of biology that deals with the structure of living organisms.

* Anatomists focus on the internal organization of organisms, including their tissues, organs, and systems.

* They use various methods like dissection, microscopy, and imaging techniques to study these structures.

While other fields like evolutionary biologists and systematists also analyze structural similarities and differences, their focus is more on understanding evolutionary relationships and classification.