In English-speaking countries, when you call someone with "Mr." or "Ms.", it means he/she is in the position to be respected, I guess. It's similar in Japan, but we Japanese use 敬称(けいしょう/Keisho = Honorific titles) much more clearly as a matter of etiquette.
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(No.1? 殿(どの/dono): Old and Classic title and we use it on business or some special occasion like traditional ceremonies, and I’m not sure this is No.1 or 2 because there are different understanding among us Japanese. But we don’t use it in our today’s daily conversation.)
No.1.様(さま/sama): The most polite and respectful way of addressing someone, which is often used today.
No.2.さん(san): A common and polite way to call someone.
No.3.くん(kun): Mainly for boys or young men
No.4.ちゃん(chan): Mainly used for girls, babies, or young boys before school
No.5.苗字で呼び捨て(みょうじでよびすて/myoji de yobisute = calling by last name without any title) :
When a person in a higher position calls someone in a lower position, or between classmates, etc.
No.6.名前で呼び捨て(なまえでよびすて/namae de yobisute = calling by first name without any title) :
Within a family, from an older to a younger such as when a parent calls a child, or an older brother/sister calls a younger brother/sister, or only when we call a partner, boyfriend, girlfriend, best friend, or someone very close.
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Here is the lines from Episode 3 : The Unsettling Matter of the Spirit;
Maomao “Please don’t call me “Lady”. You outrank me by quite a bit.”
高順「では、小猫(シャオマオ)」
Gaoshun “Dewa, Shaomao.”
Gaoshun “In that case, how’s Xiaomao?”
猫猫(小って…いきなりちゃん付けですか)
Maomao (Shaotte… Ikinari chan-zuke desuka.)
Maomao (A “Xiao” nickname? That was a sharp turn.)
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As you know, The Apothecary Diaries’ story is set in a hypothetical country modeled after China, not Japan, so the situation is a little different. Gaoshun called “Maomao-sama” first, and Maomao asked not to, then he changed to “Xiaomao: Mao-chan”, which surprised her for “a sharp turn.”
Gaoshun calls Jinshi “Jinshi-sama” because he serves Jinshi, and Jinshi calls him “Gaoshun” without title.
Maomao is just a serving girl and call Jinshi with “sama” of course, and normally Jinshi can call her “Maomao”, but he always calls her “apothecary”. Why do you think? This is a situation that we often experience… When we get used to calling her by nickname or with a title, it can be very embarrassing to change, especially to calling just by her first name. I'm looking forward to hearing Jinshi's sweet voice calling "Maomao"!
あくまで私とスコーンの付き合い方なので、異論は人の数だけあるかとは思いますが……。そういえばスコーン兵器などと書いていたら、ヘ●リアで英の作るスコーンもアレでしたね、と思い出しました。Made in 英自宅のスコーンも、単体で食べずにちゃんと色々用意して食べたら美味しく…………ならないか……。この前十数年ぶりに読み返してみたら、かわいくてニヨニヨしてしまいました。