Ultraquin (4% Hydroquinone Cream USP) or Tretinoin 0.025% Effective for Hyperpigmentation?

Which cream is more effective and faster in treating hyperpigmentation of the skin: Ultraquin (4% Hydroquinone Cream USP) or Stieva-A(Tretinoin 0.025%)? I have an indented scar on my nose that was caused from the splint which was placed on my nose following a rhinoplasty. I used Ultraquin for 3 months and noticed a difference (scar got lighter in color) but ever since I switched to Stieva-A (almost a month) I don't see much of a difference.