Fluid and responsive, can be used both for the same site?

Question

Hi, there is fluid and responsive option.
Is there any advantage to use both activated for the same site?
The only thing I can think of is when responsive design fails for whatever reason,
there's still fluid.
Or is it better to only use one of them for the same site, fluid or responsive.
Also, I'm curious about what has changed in version 6.0.0.8189 in comparison with 
older versions, no information about this onsite. 

thanks

Answer 1

Me again,

BTW, I'm asking this cause I like to use full width.
Fluid option activated doesn't seem to have an influence on design,
when responsive design is activated as well.
In File/Preference I have the default values for page width,
maximum=2000 minimum=800.
These settings are for when fluid is activated,
I can't see a difference between fluid/responsive when both are activated or when 
only responsive design is activated.
Except for images, they behave better on small screens with responsive design activated.
I can't see how it looks like above page width set to maximum=2000,
cause my max is 1366 width.
But when I set maximum=800 and minimum=600, then I see the influence of the fluid option,
then the pagewidth is restricted to 800. 
I have the idea that responsive design alone is enough and that the fluid option is
overkill in my case, except maybe if I want to restrict the pagewidth to a certain value.
Maybe in my case, full width, responsive design takes care of all browser problems, 
and the fluid option doesn't add anything.

thanks