How different is Homeric Greek from Attic? A common question, which is hard to answer or quantify.
Here’s one answer, based only on a partial review of my index cards of Attic Greek verbs.
Having looked at 213 verb cards (all fairly common Attic Greek), I found 134 in Homer, and 79 were not found. To be precise, 134 were found in “Selections from Homer’s Iliad,” by Banner; so some of the 79 might be found elsewhere in Homer, but certainly are not terribly common.
Just guessing, I’d say that there are somewhat fewer Homeric verbs NOT FOUND in Attic. A Venn diagram of the total (the union of the sets) might yield something like 50% found in both, 30% only in Attic, and 20% only in Homer.
The differences are interesting. 30 of the 79 Attic verbs not appearing in Homer are compound verbs, beginning with prepositional prefixes like απο-, δια-, εξ-, επι-, κατα-, μετα-, παρα-, συν-, υπο-. The process of grafting the prepositions onto the verbs was ongoing during the evolution of the Iliad. Interestingly, the verbs γραφω, “to write,” and αναγιγνωσκω, “to read,” are not found in Homer, a strong inference that the Iliad was originally composed in a pre-literate era. Two impersonal verbs, δει and δοκει, quite common words in Attic, are not found in Homer.
Other strictly Attic words represent the different social conditions, and the more legalistic, analytical, and political times: απολογεομαι “to speak in defense (in court),” γυμναζω “to train/exercise in a gymnasium,” δαπαναω “to spend/expend (money),” διαγιγνωσκω “to distinguish, to decide (a lawsuit),” ζητεω “to seek, examine, investigate,” κατηγορεω “to accuse (in open court),” πολιτυεω “to be a citizen, to participate in politics.”
Of the 134 that are common to both dialects, their meanings are usually the same. While shades of meaning may vary, I only found one verb, ελεγχω, with wholly different meanings: “to cross examine, prove, refute,” in Attic; “to put to shame, to bring reproach on” in Homeric.
Several verbs for very common, basic actions: “eat, go, need, enjoy, come/go,” are irregular in both dialects and, unsurprisingly, those irregularities do not match up. Some of them share the same basic root, but are spelled quite differently.