The Semantic Web represents an extension of the current web offering a metadata-rich environment based on the Resource Description Format (RDF) which supports advanced querying and inference. However, relational database (RDB) management systems remain the most widespread systems for (Web) data storage. Consequently, the key to populating the Semantic Web is the mapping of RDB to RDF, supported by standardized mechanisms. Confidentiality and privacy represent significant barriers for data owners when considering the translation and subsequent utilization of their data. In order to facilitate acceptance, it is essential to build privacy models that are equivalent, explainable, and usable within both data formats. Differential Privacy (DP) has emerged to be the flagship of data privacy when sharing or exploiting data. Recent works have proposed DP-models tailored for either multi-relational databases or RDF. This paper leverages this field of work to study how privacy guarantees on RDB with foreign key constraints can be transposed to RDF databases and vice versa. We use classical RDB and RDF formalisms as well as an established translation tool between the two (RDB2RDF) to compare DP models between the two data representations. We consider a promising DP model for RDB related to cascade deletion and demonstrate that it is sometimes similar to an existing DP graph privacy model, but inconsistently so. Consequently, we tweak this model in the relational world and propose a new model called restrict deletion. We show that it is equivalent to an existing DP graph privacy model, facilitating the comprehension, design and implementation of DP mechanisms in the context of the mapping of RDB to RDF. Conversely, we consider a useful DP model with label differentiation capabilities on graphs (QL-outedge), and propose its transposition into an original RDB distance.