Safety standards impose requirements on the process used to develop safety-critical systems. For certification purposes, manufacturers have to properly interpret and meet these requirements, which exhibit commonalities and variabilities. However, since different terms are used to state them, the comparative work aimed at manually identifying and managing these commonalities and variabilities is hard, time-consuming, and costly. In this paper, we propose to solve this problem by creating ontology-based models of safety standards and automate the comparative work. Then, we show how the result of this comparative study can be exploited to semi-automate the generation of safety-oriented process line models. To illustrate our solution, we apply it to portions of ISO 26262 and EN 50126. Finally, we draw our conclusions and future work.