THE SUN VS 400w HPS for Flowering.

ok i got 5 autos and 8 reg plants----a few are inside under a 400 and the rest are outside getting at least 6 hours of direct sun a day and the outside ones really look better than the 2 under 20/4 400 hps .the outside ones are reaching for the light ,the inside ones are growing but not reaching for the light!!!i ve been into gardening forever and i always prefer sunlight to anything inside..to me they just look healthy from nature!!!