echo hello | iconv -f ascii -t utf-16le | od -x
produces what seems to me like a big-endian result
0068 0065 006c 006c 006f 000a
whereas the same line without the le produces, on a utf16le system (OS X)
echo hello | iconv -f ascii -t utf-16 | od -x
fffe 6800 6500 6c00 6c00 6f00 0a00
Does od -x change the endianness?