float numbers in xmaxima 5.9 GCL

What gives...

MAXIMA>>>most-positive-single-float

1.7976931348623158E307
MAXIMA>>>most-positive-double-float

1.7976931348623157E308
MAXIMA>>>single-float-epsilon

1.1107651257113995E-16
MAXIMA>>>double-float-epsilon

1.1107651257113995E-16
MAXIMA>>>

So there is no difference between single and double precision
in GCL, but the largest double is 10X larger than the
maximum single??

RJF