This paper aims to explore the problematic nature of the use of adverbial connectors employed in NNS and NS academic essays by using two different corpora from Korean university students and from English native speakers in the UK. Combining corpus-based and discourse analytic approaches, the study focuses on the frequency and distributions of adverbial connectors, thus investigating in what ways this can affect the rhetorical features in terms of the text cohesion and structure. The results indicate that the Korean sample students shared the problem of other L2 writers with the overuse of overall connectors, but they showed a strong preference for using colloquial and spoken forms of adverbial connectors. On semantic relations, the overuse problem occurred in the listing, in particular, reinforcing types of the adverbial connectors. The noteworthy difference is that the mechanical repetitions of listing and contrasting ideas, and connecting them in a cause-effect sequence was identified more frequently in the Korean student texts than in the native student ones. However, counter-argument is more preferred in the argumentative context of the native student texts with more overt use of contrastive connecting items. Finally, most of the misused connectors were identified to simply repeat the ideas in the same viewpoint, which may have led to a failure in developing logical sequences in argumentative discourse. Another misuse type of connectors may derive from sociopragmatic transfer from L1 to L2. The findings thus may give some pedagogical implications for teaching alternative strategies to raise culture-specific register awareness and understand the different semantic types of adverbial connectors.