Uprated Bulbs, what ones are they and wer can i get them from?

Hi there people! Just got a stunning GPX Tip in black but wanted new headlight bulbs, all ive found out is i need either ot both 9005/9006, is there a diffrence or do i need both? I.E. 9005 dip & 9006 main!??

Best Regards,

Rob_FTO