보금자리 can mean a nest of a bird but it is also as (or more) widely used for any place that is comfortable and snug and secure for people. So you can call a temporary dwelling or practically anything that you'll return to for the night a 보금자리 if you feel secure and happy in it. 집 can mean a physical house or a family living in a house, but the latter is only if there is a cue or context for it. It sounds rather plain and boring compared with 보금자리 which has a soft and nice ring to it in addition to the special meaning like a "refuge" or "anchoring place" of one's life. 보금 is not a word used separately in modern Korean, but it seems to suggest a preciousness, since 보 is associated with precious things or treasure (보물, 보화) and 금 with gold (황금, 금반지). 자리 is essentially "a place". There is also 둥지 which more specifically means a bird's nest (and which can also be used figuratively), but 보금자리 sounds much nicer and more special than 둥지.

Well, 보금자리 might be a more difficult word (it is not Sino-Korean though) than 집, another aspect is accuracy. 집 can stand for "home" in phrases like going home or staying home and some others, but in an isolated phrase like 새로운 집, it would sound more like the physical house, so I think 집 in place of 보금자리 would have been a less accurate translation. It is also the title which is the most important single phrase in the entire story, which is probably another reason they used the most accurate and nice sounding word even if it might have been difficult for beginners.

Thank you so much, Tony for your answer and all the background information! It’s really interesting and from a readers perspective I always prefer when the author pays attention to the words, so in this case the title is almost a bit metaphorical… That being said, the source is a short story for “beginners” 🙈… I am not sure if the authors know that for a beginner it’s more likely to find some more simpler sentences and expressions and later when I am more intermediate level, then it totally makes sense to chose “meaningful” expressions and words. I am not sure if I should continue with the book, maybe it’s just to hard to understand… I am not sure! By the way I heard the word 금 already, as for the rest, it was totally new for me. Is the expression Sino Korean?