Labored is the American spelling of laboured. As a verb form it is simply the past of labor: she labored all day means she worked hard. As an adjective, though, it often does not mean “about work”. Labored breathing is heavy and difficult, as if each breath costs something — you hear this when someone is ill, exhausted, or in pain. A labored speech, smile, or joke feels stiff and slow, as if the person is trying too hard; it does not come out naturally. British writing uses laboured for all of this; American writing uses labored. Same word, same meanings, only the spelling changes.