Difference between 新 and 生?
I am a Chinese.

新 means new and 生 means unfamiliar.

In your daily study, a word you first see could be either 新词 (new word) or 生词 (unfamiliar word) to you.

However, in public articles, 新词 usually stand for newly made word (ABSOLUTELY NEW TO EVERYONE), and 生词 stand for unfamiliar word (RELATIVELY NEW TO SOMEONE).

Hope this helps.