posted by rfvv .
1. If you are stressed, you feel tense and anxious because of difficulties in your life.
2. If someone is stressed out, they are very tense and anxious because of difficulties in their lives.
The above are form Collins Dictionary.
Q1: Does it mean that there is a difference between 'stressed' and 'stressed out'? In other dictionaries, I could find that 'stressed out' is the informal form for 'stressed.' Does it mean 'stressed out' is 'stressed?
Q2: In sentence 2, why does 'they' refer to 'someone'?
Q1 - There is no difference between "stressed" and "stressed out." The latter simply has an extra word.
Q2 - "they" and "their" (plurals) are incorrect since "someone" is singular.