Mariah's covers have generally always been focused on her voice, in the production and the 'vibe' of the song, she tends not to tamper with it too much and stays pretty true to the original.
BOTH however I thought was a pretty big departure from the original which is an in your face 80s power ballad, whereas Mariah's version is much more soft and subtle with different instrumentation. The production is really lush. The only let down for me was too much reliance on whispery vocals which kind of got lost towards the start of the song (particularly the first chorus). They somewhat rectified that with the mainstream version where she added some more full vocals to the second chorus.