InnoDB is essentially the same as InnoDB-3.23.51.
If no innodb_data_file_path is specified, InnoDB at the database creation now creates a 10 MB auto-extending datafile ibdata1 to the datadir of MySQL. In 4.0.1 the file was 64 MB and not auto-extending.
This is a translation of the MySQL Reference Manual that can be found at dev.mysql.com. The original Reference Manual is in English, and this translation is not necessarily as up to date as the English version.