Question: "Could you please tell Who is Shree Subhadra-Devi in Shree Jagannatha-Kshetra? Shree Lakshmi or Shree Durga?"
Answer by Vishnudut1926: "Shree Subhadra-Devi is Shree Durga (Shree Katyayani, Shree ShivA), because "Shree Brahma-Purana", Jagannatha-Mahatmya (also known as Purushottama-Kshetra-Mahatmya) says:
नमस् ते सर्वगे देवि नमस् ते शुभसौख्यदे /
त्राहि मां पद्मपत्त्राक्षि कात्यायनि नमो ऽस्तु ते // ५७.५८ //
एवं प्रसाद्य तां देवीं जगद्धात्रीं जगद्धिताम् /
बलदेवस्य भगिनीं सुभद्रां वरदां शिवाम् // ५७.५९ //
namas te sarvage devi namas te shubhasaukhyade /
trAhi mAM padmapattrAkShi kAtyAyani namo .astu te // 57.58 //
evaM prasAdya tAM devIM jagaddhAtrIM jagaddhitAm /
baladevasya bhaginIM subhadrAM varadAM shivAm // 57.59 //
"Shreemati Subhadra-Devi is Shree Katyayani (Shree Durga) and Shree ShivA". ["Shree Brahma-Purana", 57.58-59]
भगिनीं वासुदेवस्य रुक्मवर्णां सुशोभनाम् तृतीयां वै सुभद्रां च सर्वलक्षणलक्षिताम्
bhaginIM vAsudevasya rukmavarNAM sushobhanAm tRRitIyAM vai subhadrAM cha sarvalakShaNalakShitAm
"Shree Subhadra-Devi is a Sister (Bhagini) of Lord Shree Vasudeva". ["Shree Brahma-Purana", 50.46.]
Please also pay keen attention to the fact, that according to Orthodox Vaishnava PanchaRatra there is no difference between Shreemati Lakshmi-Devi and Shreemati Durga-Devi, because Shreemati Lakshmi-Devi says in "Shree Lakshmi-Tantra", that:
1. भद्रकाली तथा भद्रा काली दुर्गा महेश्वरी - bhadrakAlI tathA bhadrA kAlI durgA maheshvarI - "I am (Shreemati MahaLakshmi-Devi) BhadraKali, Durga, MahEshwari". ["Shree Lakshmi-Tantra", 4.40] and
2. महत्त्वाच्च महामाया मोहनान्मोहिनी मता दुर्गा च दुर्गमत्वेन भक्तरक्षाविधेरपि - mahattvAchcha mahAmAyA mohanAnmohinI matA durgA cha durgamatvena bhaktarakShAvidherapi - "I am (Shreemati MahaLakshmi-Devi) also known as Shree MahaMaya and Shree Durga, Who protects Her own bhaktas like fortress!". ["Shree Lakshmi-Tantra", 4.46]
So, technically Shree Subhadra-Devi of Shree Jagannatha-Kshetra is Shree Durga, but from overall point of view and from Orthodox PanchaRatrika Vaishnava point of view Shreemati Subhadra-Devi is Shree MahaLakshmi.
And "Shree Brahma-Purana" is all about Orthodox Vaishnava PanchaRatra, because it contains a lot of Shree Vasudeva-related themes, Narayana-Mantra-Mahatmya and Vaikuntha descriptions (see, for example, #this post dedicated to Shree Vaikuntha-Mahatmya from "Shree Brahma-Purana").
So, Shreemati Subhadra-Devi = Shreemati Durga-Devi = Shreemati MahaLakshmi-Devi.
If you are very much interested in Bhagavan Shree Jagannatha, then I strongly recommend to study "Shree Brahma-Purana", it is the most authoritative source about Shree Jagannatha in this Kali-Yuga.
Motilal Banasirdass edition of "Shree Brahma-Purana" in English is great. If you know Sanskrit, you can refer either to GRETIL-version (#link) or to VedicReserve (#link)".
Answers, translations of Pramanas from Sanskrit/Hindi to English
by Vishnudut1926, Moscow, October 2018
Pramanas from "Shree Brahma-Purana" checked with Sanskrit GRETIL-version (#link) and English edition of "Shree Brahma-Purana" by Motilal Banasirdass, Volume 2, 2003 edition.
Pramanas from "Shree Lakshmi-Tantra" checked with Sanskrit-Hindi edition by KapilaDeva Narayana and English translation of Sanjukta Gupta.