This is a bit off-topic, but technically, Racket's syntax reader treats (a b c) and (a . (b c)) differently. It wraps just about every node of the parse tree in a syntax object, but the exceptions are the nodes which, from a certain point of view, aren't even part of the parse tree: The list tails which aren't written using their own parentheses. In particular, the (b c) part of (a b c) isn't wrapped, but the (b c) part of (a . (b c)) is.
Welcome to Racket v5.1.
> (define abc (read-syntax #f (open-input-string "(a b c)")))
> (define a.bc (read-syntax #f (open-input-string "(a . (b c))")))
> (define abc.null (read-syntax #f (open-input-string
"(a b c . ())")))
> abc
#<syntax::1 (a b c)>
> a.bc
#<syntax::1 (a b c)>
> abc.null
#<syntax::1 (a b c)>
> (syntax-e abc)
'(#<syntax::2 a> #<syntax::4 b> #<syntax::6 c>)
> (syntax-e a.bc)
'(#<syntax::2 a> . #<syntax::6 (b c)>)
> (syntax-e abc.null)
'(#<syntax::2 a> #<syntax::4 b> #<syntax::6 c> . #<syntax::10 ()>)
