Padres vs. parientes
While the Spanish words padres and parientes both refer to family members, they have distinct meanings and are a common source of confusion for English speakers. They are not interchangeable and refer to different sets of people within a family.
Padres
A1This word most commonly means parents, referring specifically to a person's mother and father. It is the direct equivalent of the English word parents.
Voy a visitar a mis padres este fin de semana.
(I am going to visit my parents this weekend.)
¿Cómo se llaman tus padres?
(What are your parents' names?)
La reunión de padres y maestros es el jueves.
(The parent-teacher meeting is on Thursday.)
El coche de mis padres es nuevo.
(My parents' car is new.)
Mis padres celebran su aniversario de bodas en mayo.
(My parents celebrate their wedding anniversary in May.)
Parientes
A2This word means relatives or kin. It is a broad term that includes all members of your extended family, such as uncles, aunts, cousins, grandparents, and also your parents. It is a false friend because it looks like parents but means relatives.
Tengo muchos parientes que viven en otra ciudad.
(I have many relatives who live in another city.)
La boda fue una gran reunión de todos nuestros parientes.
(The wedding was a large gathering of all our relatives.)
Mis tíos y primos son mis parientes más cercanos.
(My uncles and cousins are my closest relatives.)
Él es un pariente lejano de mi esposa.
(He is a distant relative of my wife.)
Para Navidad, nos juntamos con todos los parientes en casa de mi abuela.
(For Christmas, we get together with all the relatives at my grandmother's house.)
Summary
The essential difference is specificity. Padres refers exclusively to your two parents (mother and father). In contrast, parientes is a broad, all-encompassing term for all your relatives, including your parents, siblings, aunts, uncles, and cousins. In simple terms: your padres are two people, while your parientes could be dozens of people.