Sorry, you are wrong here. These are new tech CMH in a mogul based bulb. Yes, new. Not old school MH. They are not 'drastically' different. They are marginally different, by all of 2.4% better for the 315 CMH bulb over the 400w CMH bulb. If you do the math comparing the lumen output per watt, since you seem to like lumen comparisons so much. Actually the mogul based CMH bulb is a LOT brighter. 41k lumen vs. 33k lumen. The expected life span is the same. The color temps are the same range. The CRI is typically higher in 315w bulbs, a slight advantage, but that varies greatly between 315w bulbs. This information from GE, HTG and Phillips:
Specs from GE:
GE 400w CMH mogul based bulb
• 400 watts
• 41,000 lumens
• 20,000 hour lifetime
• 3,000K color temperature horizontal position
• 3600K color temperature vertical position
From HTG:
Ceramic metal halide (CMH) grow lights have developed quite a following in the indoor gardening industry. With a balanced spectrum and beneficial ultraviolet (UV), the output CMH bulb is closer to natural sunlight than any other type of HID grow light bulbs available. Our HTG Supply Value Series CMH system featuring the GE 400w ceramic metal halide bulb provides the bright white spectrum of a typical MH lamp combined with the powerful red spectrum of the HPS lamp for outstanding growth and excellent efficiency for outstanding growth and yields.
Typical 315w CMH bulb specs from Phillips:
- 315 watts
- 33,000 lumens
- 20,000 hour lifetime
- 3,000K-4,200k color temperature