The Russian words “нужно” and “надо” have the same meaning: “need, is necessary”, but there is a small difference between them. Let’s figure it out!
1. It is necessary to do something
If you use НУЖНО and НАДО with a verb in infinitive they both mean “it is necessary to do something”. So in this situation they are synonyms.
Мне надо пойти к врачу. = Мне нужно пойти к врачу. – I need to go to the doctor. (Literally: To me it is needed to go to the doctor)
Note: person who needs something is in Dative case: Мне нужно, другу надо, подруге нужно…
The difference between “нужно” and “надо”:
НАДО is a little bit more colloquial, while НУЖНО is more formal.
2. Someone needs something
With subjects (when someone needs something) we use НУЖЕН. (! НАДО cannot be used with a noun)
НУЖЕН is a short adjective, so it depends on the gender and number of subject (Not the person who needs something, this person is in Dative case):
m. – нужен стол
f. – нужна книга
n. – нужно окно
pl. – нужны учебники
Мне нужен доктор – I need a doctor. (Literally: A doctor is needed to me)
Другу нужна книга – A friend needs a book. (Literally: A book is needed to a friend)
Make your own example of using НУЖНО and НАДО and write them in comments