On-the-spot and On the dot

On-the-spot adjective - At the scene of action.

On the dot and on-the-spot are semantically related. In some cases you can use "On the dot" instead an adverb phrase "On-the-spot".

On the dot adverb - Just as it should be.

On-the-spot and on the dot are semantically related. Sometimes you can replace phrase "On-the-spot" with "On the dot", this phrases are similar.