Hi all, to help clarify the difference between grass cutting equipment hopefully the following will make sense.
Topper - multi blade with high ride height, not normally adjustable open front and back
Finishing mower or Roller mower - used for lawns and sports pitches multi blade and usually are height adjustable giving you a very fine cut.
Flail - either front or back mount - drum with various options of length and flail cutter type, will cut from grass through to brambles gorse etc up to small trees dependent on the machine.
Drum mower- for hay and silage only usually Tedd's the cut grass for collection.
Drum mower conditioner- same as above but with the added conditioning blades usually plastic or nylon. usually only used for silage, the conditioner section helps break down the glossy finish on the cut grass to help with fermentation.
hope that all helps, any questions just ask!