"Pomidora i sera" What the difference?
Those are both the accusative forms of the nouns, to be used when indicating the direct object of the verb. Since there is no verb/predicate to this "sentence," we must assume these word are our subject, thus we use the nominative case
They sound more like names.
For each example like this you want them to accept every possible case for each noun? Why would it be inflected when there isn't even a verb?