I wanted to show an example of what "spot" highlights are (some also call them "chunk" highlights).
This is ordered if you want highlights distributed through your hair in well defined areas rather than just two colors "mixed together". This seems to make the highlights or lowlights stand out more for those that might be after that look.
This customer actually had lowlights added to a lighter base color. It's the same thing, they are just called highlights if the smaller percentage is lighter and lowlights if it is darker.
Please keep in mind this is a piece before being sent out, so it is uncut....you can see the lowlights better in the photo with the piece upside down....sorry the photo from the top isn't better/brighter, the lowlights stand out much better in person: