A hinged floorplate magazine is an internal magazine(most hold 4 rounds) that can be loaded thur the action(bolt) when opened, one round at a time(some ww2 surplus rifles have speed loaders) Unloading is very simple by opening the floorplate..
a Detachable magazine is simply a magazine that can be removed that contains all your rounds.. And can be loaded and unloaded in the same amount of time.... IF you have more than one Magazine...
It boils down to what are your needs..
I own both types
the type of shooting I do I prefer a Drop mag