Reference architecture and product line architecture: A subtle but critical difference

Currently, the size and complexity of software systems, as well as critical time to market, demand new approaches from Software Engineering discipline for building such systems. In this context, the use of reference architectures and product line architectures is becoming a common practice. However, both of these concepts are sometimes mistakenly seen as the same thing; it is also not clearly established how they can be explored in a complementary way in order to contribute to software development. The main contribution of this paper is to make a clear differentiation between these architectures, by investigating and establishing definitions for each of them. Based on this, we also propose the use of reference architectures as a basis for product line architectures. As a result, a better understanding of both reference architectures and product line architectures, as well as an understanding of how to explore them jointly, can contribute to promoting more effective reuse in the development of software systems.