Teacher identity is complex, changeable over time, and a poly-component assembly like the social identity. Since there were some problems in analyzing teacher identity with the existing binary methods using NNEST (Non-Native English-Speaking Teacher) and NEST (Native English-Speaking Teacher), various analyzing methods were adopted in this study, such as investigating the linguistic identity of the participants. The primary purpose of the study was to investigate teacher identity of two female professors teaching English conversation in Korea and find out how their different teacher identities and learning and teaching experiences affected their teaching practices. Data collection consisted of six semistructured interview sessions with two participants and one classroom observation for six months. To triangulate the data, the study analyzed the classroom observation field notes and background survey sheets along with the transcripts of the interviews. The present study discovered that the first participant (EB-elective bilingual) positioned herself as a NNEST and Korean who spent most of her lifetime practicing and teaching English in Korea with studying experience for about three and half years in the U.S. In the meantime, the second participant, a circumstantial bilingual, perceived herself as a NEST and Korean, who studied and practiced English in the U.S. and in some Asian countries but taught English language mostly in Korea. Even though both professors confessed that a well-prepared class was important, their different linguistic identities, learning and teaching experience caused the different teaching practices. In addition to such findings, the present study attempted to uncover the relationships between teachers' NNEST identity and their actual teaching practices in the classroom. Hence, this study offers important implications for teaching English conversation in EFL (English as a Foreign Language) contexts.