Well,
You could say that 0.04 is greater than 0.004.
0.04 > 0.004
You could be more specific and say how much greater 0.04 is compared to 0.004.
0.04 = 10(0.004)
You can also make general conclusions about the two numbers.
"0.04 and 0.004 both are less than 1."
"Both numbers have fractional forms that can be simplified."
"Both numbers have a zero to the left of the decimal point."
And so on and on.