-zione and -sione are two suffixes (not the only ones) that are present in nouns derived from verbs. Their counterparts in Latin (where they originated) were -tion, -tionis and -sion, -sionis. As for your examples, "confusione" comes from Latin confusio, confusionis (from the verb confundere), while "lezione" comes from lectio, lectionis (from the verb legere). Other examples are (here I list them along with the Italian corresponding verb instead): apparizione (apparire), distribuzione (distribuire), informazione (informare), operazione (operare), correzione (correggere), aggressione (aggredire), accensione (accendere), invasione (invadere) Some references: http://www.treccani.it/vocabolario/sione-zione/ http://www.treccani.it/enciclopedia/sione-o-zione_%28La-grammatica-italiana%29/