Mottling is variable too- some birds have mottling only at the very tips, while others have quite a lot of white, nearly a third to about half of the feather.
Mottling also changes according to age- the amount of white tends to increase with age.
Look at mottling this way: the budding feather "starts out" white then the color "turns on" for rest of the feather.
Splash is extremely variable, they can be off white to greyish to light bluish background, the speckles can range from very few to very very many.. the speckles can be all tiny, medium size or even a couple large patches of color or a mix of all. The difference is, the speckling is completely random, with no clear pattern. A single feather from a splash can be solid colored, has speckles, has a streak of color(again completely random).
It's hard to tell what you mean by large patches of white. If most of the feathers are colored with white tips(doesn't matter if the white tips are large or small, as long as rest of feather is colored) then it is mottled.