Food, aliment, pabulum, nutriment, nourishment, sustenance, pap are comparable especially when they denote material which feeds and supports the mind or the spirit.
Food is applicable to whatever is taken in and assimilated to enlarge the mind or spirit or to contribute to its vitality and growth.
Aliment and pabulum are not always distinguishable from each other, but aliment is more often applied to what nourishes or builds one’s mind and nature and pabulum to something, and often something overrefined, bland, or worthless, which serves as an article or sometimes as the substance of one’s mental diet.
Nutriment and nourishment are both applied to what is needed for healthy growth (as of the body, the mind, or an institution), but nourishment in addition suggests, as nutriment does not, the nourishing effect produced.
Sustenance stresses the supporting and maintaining rather than the upbuilding aspect of nutriment.
Pap is found chiefly in contemptuous or ironical use and applies in its extended sense to nourishment that is as slight, as diluted, and as innocuous as soft bland food for an infant or invalid.