Can Any One Tell Me What's Going On?

Can anyone tell me what these lighter green almost "stretch mark" looking parts on my leave are from? They are only happening on the plant in the right bucket while the the other plant shows no signs. They both look healthy except for these lighter green parts on the leaves of the right plant.

Looks like two different strains if the case. the right one may need a little more Nitro to get it green. since on hydro setup. mist with some nutes to bring it back to a rich dark green. had a similar problem and did not know until the end of veg. ;P good luck and keep on smokin'.