Services are ubiquitous and are a critical element of the modern world economies. They play an increasingly important role in most industry sectors including Information Technology (IT). The essential differences between a software product and an IT Service are unclear. IT services are seldom offered in isolation and are often packaged and provided with software products. More so than before, IT service providers need to conduct a rigorous and systematic elicitation, and analysis of the needs and requirements of the intended users so that the resulting IT services are closely aligned with the enterprise business needs. This paper presents a comparative study of software and IT services from the Requirements Engineering (RE) perspective, both from process and product viewpoints. The overall aim of this compare and contrast is to investigate key similarities and differences between software and IT services in order to ascertain the applicability and relevance of RE research and practice results for eliciting, analyzing, documenting and managing IT services.