Is a word [letter] and [scripture] in 2 Peter 3:16 the same meaning?

2 Peter 3:16 > He writes the same way in all **his letters**, speaking in > them of these matters. **His letters** contain some things that are hard > to understand, which ignorant and unstable people distort, as they do > the other **Scriptures**, to their own destruction. I mean, when Peter said "*his letters*" ---> Did Peter mean [his Scriptures] ? ---------- As I'm from a non-English speaking country, this is quite confusing for me. Because in our language words, a Scripture is a Bible - while a letter is not a Bible. And of course, in this modern time - no one will say "I'm writing a Bible" :). Illustration :
Suppose Peter is writing for his fellow Christians.
Someone phone him *"Hi Peter, what are you doing ?"*.
Peter answer "I'm writing a scripture".
What will be in the caller's mind ?
A. Peter is writing a Bible
B. Peter is writing a letter (not a Bible)
Thank you.