Honestly, I've never seen a difference with sleep and standby. If you put the device in standby and put it in a magnetic holster, when you remove it it wakes up. So, I figured standby is the way to put the device to sleep, as if it's in a holster, without putting it in a holster. However, in standby I don't think your "in holster" settings under profiles will take effect. But all else, appears the same. Call it "Battery Saving Pocket Mode."