In this paper I try to establish the following differences between Epicurean and Lucretian psyches:
1. For Lucretius, the psyche is composed of particles of air, breath, heat, and a fourth unnamed constituent. Epicurus suggests that the psyche is composed of a single kind of atom, and that it in some way resembles heat and in some way resembles breath.
2. For Epicurus, breath and heat are properties of compounds, not kinds of atoms or kinds of compound entities. Lucretius apparently takes the opposite position.
3. For Lucretius, the components of the psyche seem to be entities larger than atoms.
Harrington, K. W., "Epicurus' Conception of the Psyche" (1976). The Society for Ancient Greek Philosophy Newsletter. 82.