Brett or Reduction, Can You Tell The Difference?

Ok so which one was affecting a wine i had last night? On the nose - and lasting the entire 2+ hours it was in my glass - it was incredibly stinky in an earthy/ merde kind of way. On the palate it cleaned up a bit and suggested a beautiful wine was underneath. But the nose remained very offputting to me all night. The wine alongside had a bit of similar stink that blew off. Neither smelled of garlic or smoke.