This case-sensitive code system http://hl7.org/fhir/structure-definition-kind defines the following codes:
Code
Display
Definition
primitive-type
Primitive Data Type
A primitive type that has a value and an extension. These can be used throughout Resource and extension definitions. Only the base specification can define primitive types.
complex-type
Complex Data Type
A complex structure that defines a set of data elements. These can be used throughout Resource and extension definitions, and in logical models.
resource
Resource
A resource defined by the FHIR specification.
logical
Logical Model
A conceptual package of data that will be mapped to resources for implementation.