Different pin assignment for same regulator
I see no difference in the pin outs at all: -



TI's offering in red box; ONsemi to the right and lower


  Why do the manufacturers don't follow a logic layout (e.g. PIN 1 =
  INPUT and 3 = OUTPUT like all(!) LM7805)


Generally they don't and, unless I'm being really stupid they don't for the LP2950.