There are 150 levels. The minimum and maximum level is defined by the hardware of the driver. The ramp in-between is created in a way that it should appear more or less linear. This works quite well for the regulated 7135 channel. But for the FET channel you don’t know the actual brightness, so it will behave differently.
Perceived brightness is very different from actual power. For something to appear twice as bright you need at least four times the lumens. Also the output of LEDs is not linear, so you need even more than four times the power. Here is the current vs lumen graph of a random LED: XHP50.2 J4 4000k output test by Texas_Ace - Really impressive improvement from the last gen
Both has nothing to do with Anduril 1 vs 2, it’s just different hardware. There are some tricks to lower the minimum brightness in software, but very specific to a particular driver.
The default ceiling was changed for the SP10 because it is not a high power flashlight and level 150 should be safe to use on a regular basis.