Work, on the other hand, has a defined start and endpoint. Ideally, it produces something enduring and unique.
In ancient times, labor was looked down on as something that slaves did. The lowest in society did the back-breaking, life-sustaining work anonymously, while rich, propertied elites built empires, wrote philosophy, and invented new technologies.
The world has changed since then, but I think there's something useful in that distinction. Capitalism transmutes nearly all work into labor. Almost every profession feels like it's performed solely to "sustain life" whether it's plowing fields or producing software. It's all just a salary. So I'm not surprised when I hear that people feel they have "nothing to show for it": they usually retain no ownership of the things they create and it all seems like one long endless task.