Given the complexity and growth of the International Classification for Nursing Practice (ICNP®), from 2005, it began to be developed by ontology. Researchers at the discussion group "Sistemas Classificatórios para as Práticas de Enfermagem e Ontologias" at the Health Technology Postgraduate Program (PPGTS) at Pontifical Catholic University of Parana (PUCPR) began, in 2009, building an ontology which had as initial basis the vocabulary inventory of the Classificação Internacional das Práticas de Enfermagem em Saúde Coletiva (CIPESC®) - Brazilian contribution to the ICNP®. In order to promote interoperability between different representations of the elements of nursing practice, this study aimed to analyze comparatively the ICNP® 2.0 Ontology and CIPESC® Ontology and to identify similarities and differences between them. This is a documentary, exploratory and descriptive research, of quantitative approach, whose methodological course was divided into four steps: identification of ontology elements in the different versions of ICNP® and in the vocabulary inventory of CIPESC®; analysis of ICNP® 2.0 Ontology; analysis of CIPESC® Ontology; and alignment between the ICNP® 2.0 Ontology and CIPESC® Ontology. The ontology elements considered for analysis in this study were: concepts (or classes), instances (or individuals), properties, relationships, constraints, and axioms. The results point to the identification of concepts (or classes), properties, relationships, constraints, and axioms in ICNP® and in the vocabulary inventory of CIPESC® when considering the characteristics of their axes and hierarchies of terms structures, as well the identification of structural characteristics of ICNP® 2.0 and CIPESC® ontologies, in light of ontology elements. From the alignment of ontologies through Protégé software, it was verified that of the 2.897 concepts in the ICNP® 2.0 Ontology and of the 932 concepts in the CIPESC® Ontology, 215 are corresponding between both ontologies, 2.682 are present only in ICNP® 2.0 Ontology and 717 are present only in CIPESC® Ontology. It was concluded that the identification of correspondences between entities of ontologies that represent the elements of nursing practice is essential for interoperability between different terminologies, but should not be limited to the application of computational algorithms, but should also consider the definitions of the concepts in the context of Nursing. It is emphasized the need to use technological resources for the development and exchange of information between nursing terminologies facing the complexity demanded by the management of the nursing language concepts by ICNP® and inventory vocabulary of CIPESC®.