can you explain the difference between 'nandesuka?' and 'nandeshouka?' also can you tell me how to translate" 私と一緒に帰らない?" I'd translate it into "Why don't you come home with me?" or "How about if we go home together?" I don't really understand how -nai is used in question so I'd be thankful if you could explain it too ^^
For なんでしょうか and なんですか do you think you could give me an example or some context? The meaning can be different depending on the situation you are talking about.
For 私と一緒に帰らない I would translate it to something like “won’t you return with me?" In this sense it’s similar to ない since you are using a negative in “won’t" to ask a question politely or to give a suggestion. ない is kind of like “won’t you?" or “wouldn’t you?" to be more indirect than something like 私と一緒に帰る or just “return home with me" period. Saying it like this is less forceful and gives the listener more of a choice.
私と一緒に朝ごはんを食べない。(watashi to isshyo ni asa go han wo tabenai) - Won’t you eat breakfast with me?
vs. the blunt and direct “eat breakfast with me."
私と一緒に映画を見に行きませんか。(watashi to isshyo ni eiga wo mini ikimasenka) - Won’t you go watch a movie with me?
vs. the forceful “go watch a movie with me."
This is common when you are offering people things out of politeness:
お茶でも飲まない。(ochya de mo nomanai) - Won’t you have some tea or something?
Things like this would be said with a rising intonation at the end to indicate that you are asking someone something.