Bison %nonassoc vs %token?

I've read a lot of sources, but yet can't understand what's the difference between: %nonassoc and %token?

I understand the difference between %left and %right but for me the first two sound the same.

I hope if someone can give me few examples to understand when I need to use %nonassoc and when to use %token?

to use %token?
to use %token?
to use %token?

%token is the basic way to declare a terminal.

Using %nonassoc will throw a syntax error if there is any precedence ambiguity.

From my experience, you shouldn't need anything other than %token for the terminals.

Here is the relevant section from $ info bison

3.7.3 Operator Precedence
-------------------------

Use the ‘%left’, ‘%right’, ‘%nonassoc’, or ‘%precedence’ declaration to
declare a token and specify its precedence and associativity, all at
once.  These are called “precedence declarations”.  *Note Precedence::,
for general information on operator precedence.

   The syntax of a precedence declaration is nearly the same as that of
‘%token’: either

     %left SYMBOLS...

or

     %left <TYPE> SYMBOLS...

   And indeed any of these declarations serves the purposes of ‘%token’.
But in addition, they specify the associativity and relative precedence
for all the SYMBOLS:

   • The associativity of an operator OP determines how repeated uses of
     the operator nest: whether ‘X OP Y OP Z’ is parsed by grouping X
     with Y first or by grouping Y with Z first.  ‘%left’ specifies
     left-associativity (grouping X with Y first) and ‘%right’ specifies
     right-associativity (grouping Y with Z first).  ‘%nonassoc’
     specifies no associativity, which means that ‘X OP Y OP Z’ is
     considered a syntax error.

     ‘%precedence’ gives only precedence to the SYMBOLS, and defines no
     associativity at all.  Use this to define precedence only, and
     leave any potential conflict due to associativity enabled.

   • The precedence of an operator determines how it nests with other
     operators.  All the tokens declared in a single precedence
     declaration have equal precedence and nest together according to
     their associativity.  When two tokens declared in different
     precedence declarations associate, the one declared later has the
     higher precedence and is grouped first.

%token declares token(s)

%nonassoc declares token(s) AND sets their precedence

%left/%right declares tokens AND sets their precedence AND sets their associativity

So which you use depends on whether you want to not set the precedence at all, or set just the precedence, or set both precedence and associativity.

So what is the difference between precedence and associativity? They're both for resolving shift/reduce conflicts when there's a conflict between shifting a token and reducing a rule containing a token¹ with predence (and possibly associativity). The precedence is for when the tokens in question are different (or at least have different precedence), while the associativity is for when the tokens are the same (or at least have the same precedence)

¹_{Yacc is actually comparing the precedence and associativity of the rule to be reduced with that of the token to be shifted. It's just that rules always get precedence/associativity from a token (either one in the rule, or one specified with %prec)}