There are three words to refer to somebody else's daughter (According to my dictionary): 娘さん、お嬢さん、令嬢。
There are also three words to refer to somebody else's son: 息子さん、子息、坊ちゃん。
What are the differences between these words? I'll assume politeness, but in what order, and when is each more commonly used?
Similarly, what about 夫 and 主人 for your own husband? And possibly more family terms that are similar like this?
As you stated, the difference really is in politeness.
As you may have already noticed, there are different kinship terms for several situations:
I'm not going to through each and every term, but generally speaking, most if not all of the terms in (2) and (3) end with さん, while the ～さん suffix can be replaced with ～さま for a more respectful situation (お嬢様{じょうさま} for example) or ～ちゃん for a more casual situation (息子ちゃん{むすこちゃん}).
Also note that under situation (2), there are a lot of terms when you address a person by his name. Let me know if you want a more specific list.
The terms without any ending, are usually used in situation (1).
令嬢{れいじょう} is, according to Yahoo Dictionary, a (a) nobleman's daughter, (b) a more respectful way of addressing someone else's daughter.
In addition, according to this comparison between some of the ways to say 'daughter' in Japanese, 令嬢{れいじょう} is an old word (and therefore, less common in modern Japanese).
You may attach the prefix ご to the word for a even more respectful nuance.
For all I know, 令嬢{れいじょう} doesn't take an ending, since it already a respectful word by itself.
坊ちゃん{ぼっちゃん}, is
お坊ちゃん{ぼっちゃん}).I'd say this address is usually for small boys (hence the ちゃん) but I'm not too sure.
Also, to me, this sounds to me like those words that you should carefully use since it may come out as an insult in some situations.
子息{しそく} is simply another word for 息子{むすこ}.
One interesting thing about it, is that in Yahoo Dictionary, one of its definitions is literally "someone else's child". No gender specified.
Personally I've never seen it used without a suffix/prefix, and in any case I think 息子{むすこ} is much more common.
As for husband, both 夫{おっと} and 主人{しゅじん} are grammatically interchangeable in situation (1) but, only 夫{おっと} can be used to informally address someone else's husband (situation 3).
The formal way would be ご主人{しゅじん}. Furthermore, (ご)主人{しゅじん} can be used to also address a master, a boss, and landlord or lady, and not just husband, unlike 夫{おっと}.
One thing to note is that using 主人{しゅじん} in situation (1), may sound a little chauvinistic(?).
And for extra, some of the words under situation (3), which can be used for addressing strangers as well:
お兄さん{にいさん}, お姉さん{ねえさん}, 叔父さん{おじさん}, 叔母さん{おばさん} and お嬢さん{じょうさん}.
There is an awesome kinship terms chart (from which I took some of the info above) in the Nihonshock Japanese Cheat sheet which is pretty awesome by itself.
This is my first time answering a question here, hope it helps!
