Don't know about run time but the lights are the same size. Both seem to be about as bright. The snap doesn't swivel on the nano and the joint is about the mid point of the tube. The joint on the pico light is on the head of the light. In operation the pico light is easier to turn on one handed due to the placement of the joint (switch), and you can turn on the nano with one hand it just takes a bit more dexterity. Both use four small button batteries. Both have a O-ring seal, the pico light looks to have a better seal placement to keep the light dry.

Here is a side by side picture if it will help,



Sorry my pictures are not as cool as Schwert's.