When you equip a Sentry with a Laser or Light, it remains on.
However, if you equip a Mannequin with a Head Lamp, it does NOT remain on.
Side note 
: Could you add a color slide bar to Mannequins, as of now they can only be white, which make them easily be recognized as dummies. Non of my characters are pale white.
Mate
One is active and the other isn’t
Imo what difference does it make. lights and lasers on sentry’s are useless cause they see you regardless of light level
I think it’s supposed to be that way. The reason is that it would make the spotlight useless, as it would just be making a mannequin and putting a head lamp on it, and for players like me, who use generators practically just for spotlights, never use these. So I think it’s best that they stay that way.
Lights in both sentries and mannequins are useful when defending a LIVE RAID vs a large group because you can see further in the darkness of night as sentries have a 180 degree rotation, mannequin with light can count as another defender, specifically when the invading force are double your numbers. But if your tendency is to just log off, you won’t be facing my needs.