Introduction. The modern context of a practical shift towards the service sector requires to study it from a theoretical perspective. Despite a sufficient number of publications on the topic of services, many authors do not provide corresponding grounds when identifying classification groups of services. This article focuses on the specific aspects of clarifying the concept of "service", essential classification of services and functions. Materials and Methods. The theoretical basis of the research included articles from peer-reviewed journals and monographs on the topic under study. A wide range of general scientific methods was applied in the research, including analysis and synthesis, abstract-logical, systemic analysis and others. Results. Characteristics of material and immaterial services were provided in comparison, which allows for a better emphasis on the features of their provision and consumption. This approach takes into account the specifics of consumers and their role in the process, as well as the qualifications of the personnel when planning activities in the service sector. Important issues of service compatibility and service function allocation are addressed. The study highlights the need to include education and culture in the value-oriented function of services. Due to the inability of consumers to clearly express their social and spiritual needs, the authors argue for the importance and tasks of service industry workers to assist clients in forming their essential needs. Conclusions. The article compares the most important characteristics of service differentiation based on various classifications, including its specificity, evaluation, producers, producer-consumer relationships, and production technology.