Information technologies with their strong penetration can provide effective solutions for addressing the challenges faced by the manufacturing industry. Leveraging information technologies to enhance the competitiveness of the manufacturing industry has become a prominent trend worldwide. In this context, two important concepts for manufacturing—Industry 4.0 and cloud manufacturing—have been proposed. Industry 4.0 refers to the fourth industrial revolution, which is characterized by the widespread application of cyber-physical systems (CPS) in the manufacturing environment. Cloud manufacturing is a new service-oriented business paradigm based on the cloud concept and method. Since their inception, there has been a great deal of attention from both academia and industry. However, to date, they have largely been addressed in isolation. The fact is that, although being proposed from different perspectives and embracing different ideas, they each have some key features that can benefit one another. In order to better understand these two concepts, there is a need to compare them and clarify their relationship. To this end, this paper presents basic ideas of Industry 4.0 and cloud manufacturing, gives a brief overview of their current research, and provides a detailed comparative analysis of them from different perspectives.