I believe hdmi can give you a better picture but both are not the same, component is analogue and only carry’s the video signal where hdmi is digital and carry’s both video and audio.
Quality can also very from player to player, ie. a cheaper player that has both may not output a very good picture on the hdmi out but a better picture on the component out where as a higher end player should in theory give a much better picture on the hdmi than component due to in using better hardware. Cable quality can also play a part in the quality you get.