Universal ideas are things like apply to all human beings--we all love, we all fear, we all experience jealousy, love, hate, courage, cowardice, anger, compassion, etc.
Universal parent-child themes include parents worrying about child's safety, and how or if they will grow up; whether or not they always can be there for the child; whether or not they are a good parent; what to say when you don't have all the answers, etc.
Unique aspects include things that happen in one or a few families but certainly not all. Some children grow up living with war rather than peace; some with two parents, others with one, one or even more than two; some kids are adopted;
Unique, in the instruction about, might also include something creative about the manner in which the author chose to write.
I have not read these selections, but I hope this helps.
