A concrete syntax tree (parse tree) is the syntax tree that stores the full representation of the parsed document.
It's is a low level representation of the parsed source in the structure defined by a grammar description. It should be possible to rewrite the original document for a concrete syntax tree.
It represents every detail (such as white-space in white-space insensitive languages)
This is the first tree build by a parser.
As a second pass, the parser would create an abstract syntax tree that holds only syntactic information. For instance, for literal: