The purpose of this research is to examine the variables that influence buying behavior for a sample of social network sites users who are offline buyers of hospitality services. Subsequently, we do the same of social network sites users who are online buyers in the same sector. Finally, we compare both types of clients and discuss their different purchasing behavior. Logistic regression is used to model the dichotomous outcome variables. The dependent variable was to buy or not to buy a tourist service and the independent variables were: the social network sites use, social identity, altruism, telepresence, and Word-of-Mouth. The data set was collected in Chile and Spain from a sample of on-line questionnaires. The main result of this study is the clear difference in consumer behavior between people who buy online tourist services and those who buy these services in travel agents or other traditional channels. The main contribution of this paper deals with the influence of social network sites on offline and online shopping in the hospitality sector.