I would like to ask about the following words: 父親【ちちおや】 and 母親【ははおや】. They refer to father and mother, right? But why do they exist? When do we use them instead of お父【とう】さん and お母【かあ】さん?
I have a similar misunderstanding regarding the following two words: 両親【りょうしん】 and 父母【ふぼ】
Basically they both mean parents or 'father and mother', but what is the difference?
Thank you for your help in advance! Have a nice day!