They are both very heady and agressive scents, they both open with some pretty heavy adehyde or aromatic action (I can't decide which--maybe both). There might be a touch of pseudo citrus--bergamot if I remember correctly-- in Kouros opening--which would be vaguely reminiscent of the orange in Orange Spice. The civet and honey in Kouros's drydown might suggest the Creed basenotes. They have a similar potency in sillage. Those are the only similarities I see. After the first 4 minutes, Orange Spice continues to be a citric scent, staying fun and playful (for a Creed), while Kouros moves to deeper incense and leather tones and a darker ambiance.