According to http://pubs.opengroup.org/onlinepubs/9699919799/:
By default, the standard output shall contain an entry for each input
file of the form:
"%d %d %d %s\n", <newlines>, <words>, <bytes>, <file>
If the -m option is specified, the number of characters shall replace
the <bytes> field in this format.
If any options are specified and the -l option is not specified, the
number of <newline> characters shall not be written.
If any options are specified and the -w option is not specified, the
number of words shall not be written.
If any options are specified and neither -c nor -m is specified, the
number of bytes or characters shall not be written.
If no input file operands are specified, no name shall be written and
no <blank> characters preceding the pathname shall be written.
If more than one input file operand is specified, an additional line
shall be written, of the same format as the other lines, except that
the word total (in the POSIX locale) shall be written instead of a
pathname and the total of each column shall be written as appropriate.
Such an additional line, if any, is written at the end of the output.
So it would seem that neither implementation is strictly conforming, as the standard seems to dictate that there should be 2 leading blanks. Standards are a funny thing.