Harder or Easier?

       I suspect it may depend mainly on whether you're H & S @ work, or ex-Fire Service.
BUT
       Once upon a time we could tell, as far away as you could see colour, what was in an extinguisher - thus - Red = Water : Cream = Foam : Black = CO2 : Green = BCF (Brace yourself) BromochlorodifluoroMethane.  I retired in 1996 so things may well have changed - BUT - I have a faint recollection of a panic ensuing over the effects of Halons on the O3 (Ozone) Layer.
      From the shape of "delivery" you'd get a further clue.  Water was only a jet, while Foam and CO2, in my day, had "horns" like the right one, which expands 450X  as it leaves the extinguisher.
another - BUT - 
       Now you only know it's a Fire extinguisher because it's red, even the Foam have lost their erstwhile horn.

MORAL? - IF you are ever likely to need one, read it NOW and NOT while your Bum's gently smouldering.