Visual Representation

When the REPL prints a binary, it uses the notation #B(...) (or sometimes <<...>> if you're looking at Erlang documentation). The contents are displayed as integers, each representing a byte:

lfe> #B(1 2 3)
#B(1 2 3)

If the binary happens to contain bytes that form printable ASCII characters, the shell might helpfully display it as a string:

lfe> #B(72 101 108 108 111)
#"Hello"

Note the #"..." notation for binary strings. This is the shell being clever, recognizing that the bytes 72 101 108 108 111 correspond to the ASCII codes for "Hello" and presenting them in a more readable format. The bytes haven't changed—only their cosmetic presentation has been upgraded for human consumption.

This is similar to how the number 42 and the string "42" are different beasts, even though they might occasionally be mistaken for each other at parties. One is a numeric value; the other is a sequence of character codes that, when interpreted by a human visual system, evoke the concept of forty-two. The distinction matters more than you might think.