Categorisation is a central issue in Cognitive Linguistics, which is argued to be one of the primary principles of conceptual and linguistic organisation (Croft & Cruse, 2004). Classical categorisation and the prototype theory are two general approaches to categorisation. Since the classical categorisation approach was claimed to have certain drawbacks, most linguists working within the experimentalist mode of explanation use prototype categorisation as their primary way to account for their data. However, is the way people categorise items around them consistent across different cultures? This paper attempts to shed light on the answer to this question by comparing the prototype structures of four categories - bird, furniture, fruit, and vehicle - between English and Vietnamese. In order to find out the similarities and differences, the questionnaire data from 92 Vietnamese participants were collected to survey their rating of the goodness of exemplars. The data were then analysed by Google Form and compared to the available data from English respondents in the previous study of Rosch and Mervis (1975). Results revealed that the prototype structures were similar and different across the two cultures. That is why the teaching and learning of vocabulary should take into account cultural sensitivity.