두 단어 사이에는 큰 차이가 없지만 설명하려고 노력해 볼께요. 기차역 Tren istasyonu 지하철역 metro istasyonu 버스 정류장 Otobüs durağı 보통 버스와 지하철에서 Sonraki durakta ineceğim. '다음 역에서 내릴께요' 라고 말을 하려면 istasyon 말고 durak 이라는 말은 사용됩니다. 그런데 기차에서 durak 대신 istasyon 이라는 말은 사용됩니다.

Hello, the word Durak comes from the verb durmak (stopping) and it's mean the area where the bus or subway stops, istasyon exactly means station and the two words can be used in the same sentence or situation.

Umm there is no semantic difference here. But istasyon is only used for railways and durak is used for rest of transportation( busses, metro, ferry) İstasyon is obviously a loanword (station). Durak is Turkish. The reason i think would be in the times of Ottoman Empire. Those times we had trains but no highways. In Ottoman era people didn't care about foreign word usage. Only after republic, with the establishment of Türk Dil Kurumu, we removed some foreign words and replaced them with forgotten Turkish words or new words created from original Turkish roots. Durak is one of these new words. But sometimes people simply didn't stop using some of the removed words (they already had a word for train stations istasyon, they didn't switch to durak for them. But for busses. It was a new thing and for that, the usage of durak was promoted). There were cases of people didn't accept new words too. No one uses sepettopu for basketball. So istasyon is one of these lingering words.