Just bought a new 600W HPS system! 2 Different bulbs! Which One Do I Use?

http://www.google.com/products/catalog?ds=pr&pq=600w+grow+light&hl=en&cp=15&gs_id=1r&xhr=t&q=600w+grow+light&safe=off&client=safari&rls=en&gs_upl=&bav=on.2,or.r_gc.r_pw.&biw=1280&bih=888&um=1&ie=UTF-8&tbm=shop&cid=8927203049686359104&sa=X&ei=Mn1MTp69HfTKiALssYWpAQ&sqi=2&ved=0CGwQ8gIwAA


^^
This Is What I Bought And If U Notice It Comes With 2 Different Bulbs. My Plants Have Just Started The Flowering Process, I Need 2 Know If 1 Bulb Is Better Than The Other (One Fat, One Skinny)

use the mh for veg and the hps for flower

fat is the mh and skinny is the hps...follow ganjaplantaa's advice