Often heard on the R/T is controllers telling pilots to

a) reduce now to final approach speed

or when they're really worried

b) reduce NOW to minimum safe approach speed (6 departures/runway inspection/tractor crossing etc etc ahead)

now...in a modern airliner, is there any difference whatsoever between final apc speed and min safe speed?
I assume it unlikely that having programmed vref speeds etc that the crew will suddenly dump more flap/thrust and slow further? But then thats better than a go around? Pilots only please...

They are the same. There may be something in the Controllers' documents, but there is no difference to me.

If I have planned a Flaps25 landing, I do NOT change that to Flaps30 because of a controller's request for some speed. I MIGHT tell them ahead of time (as our station guide recommends at ORD) what our final approach speed will be when we first talk to Approach...

ditto

ATC may also say something like...''s turn if able to accomadate departures''