From my understanding, daimons are a race of beings that are immortal, but they are not gods. Like they are above humans but below gods.
The word daimon in Greek (δαίμων) generally just meant "divine power." It's god in the abstract. This is especially true at the earlier stages of Greek literature, such as in the Homeric epics. All gods are daimones, but not all daimones are Olympians.
The Greeks had many different types of divinities, in myth differentiated by parentage. In practice, though, the gods that populate the world come in all different forms, and they can all be called daimones. This would include the Titans, the Olympians, nymphs, ancestral souls, tutelary deities, and other types of spirits.
In this sense, daimon is most similar to the Shinto kami.
As time went on, it generally referred to the more powerful gods, chiefly the Olympians and Titans, less and less. By the Roman era, "spirit" is the better translation.
See for yourself all the different ways the Greeks used this word.