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The Korean Association for the Study of English Language and Linguistics
[ Article ]
Korea Journal of English Language and Linguistics - Vol. 25, No. 0, pp.1378-1394
ISSN: 1598-1398 (Print) 2586-7474 (Online)
Print publication date 31 Jan 2025
Received 18 Jul 2025 Revised 22 Aug 2025 Accepted 16 Oct 2025
DOI: https://doi.org/10.15738/kjell.25..202510.1378

Exploring Vocabulary Patterns in ESL and EFL Learner Corpora: Implications for Language Teaching

Seulgi Choi ; Sunyoung Park ; Jin-young Tak
(First author) Master’s Student, Department of Artificial Intelligence and Language Engineering Sejong University csg0726@sju.ac.kr
(Co-author) Visiting Professor, Daeyang Humanity College Sejong University sunpark@sejong.ac.kr
(Corresponding author) Professor, English Data Convergence Major Sejong University jytak@sejong.ac.kr


© 2025 KASELL All rights reserved
This is an open-access article distributed under the terms of the Creative Commons License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Vocabulary knowledge is a crucial determinant of writing proficiency and overall communicative competence for second language learners. While previous research examined lexical richness in academic writing, few studies have directly compared English as a Second Language (ESL) and English as a Foreign Language (EFL) learners. This study attempts to fill that gap by analyzing vocabulary use in written texts from EFL learners and ESL learners, focusing on how different learning environments influence lexical development. Using the Linguistic Feature Toolkit (LFTK), an open-source tool with over 220 linguistically defined features, and the International Corpus Network of Asian Learners of English (ICNALE), the study systematically examines lexical features across groups. The results of the current study found interesting patterns between ESL and EFL learners. ESL learners, immersed in English speaking contexts, demonstrate greater lexical flexibility and diversity in content word usage that closely aligns with native speaker patterns. In contrast, EFL learners exhibited more native-like patterns in functional word usages. This phenomenon can be interpreted as that ESL learners develop greater diversity in content word usage as a result of immersive exposure, whereas EFL learners, through form-focused instruction, developed functional word usage patterns more similar to native speakers. These results have important pedagogical implications: AI-based vocabulary learning tools can simulate immersive exposure for EFL learners, promoting lexical diversity and motivation, while ESL learners may benefit from explicit instruction targeting functional words to improve grammatical precision. Ultimately, the study emphasizes the importance of tailoring instruction to learners’ environments to support balanced language development and effective writing outcomes.

Keywords:

vocabulary development, lexical diversity, EFL learners, ESL learners, writing proficiency, pedagogical implications

Acknowledgments

Seulgi Choi and Sunyoung Park contributed equally to the conception and design of the study and share first authorship.

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