Is each of the following a different character?
0 O o
Yes. Each of the above ("zero," "Capital O", and "lower case "o") is a different character and will have a completely different 16 bit code.
In a program, a character literal is surrounded with an apostrophe on both sides:
'm' 'y' 'A'
In a program, control characters are represented with several characters inside the apostrophes:
'\n' '\t' '\377'
Each of these is what you do in a program to get a single char. The first one represents the 16 bit newline character, the second on represents the tabulation character, and the last one is the delete character. (The Java documentation has a complete list.)