Well, can you please insert a reference to these sentence? Are they just something you heard? Let's start saying that "primo" means "first", while "prima" means before. I'll just write a couple of examples in order to make you understand the use of "primo/prima" [1] "Fai come ti dico: Primo: prendi il libro; secondo: leggi e studia; terzo: ripeti ad alta voce" In this example "primo" "secondo" and "terzo" are ordinal numbers, and they are used in a sort of list of things to do; it would have been the same writing them like numbers; this is a "raw" translation: "do what I say: first (thing to be done): take you book; second...." [2] "Prima di stampare il documento, salvalo." In this example "prima" will be translated with "before": "save your document before printing it". In my opinion in your sentence these uses of primo/prima have been mixed... The first sentence, in my opinion, should have used "primo", unless they delete the comma. in that case the sentence will be "prima ho finito un tema", but it will be an incomplete sentence, like "i've first ended the composition...."; in that case i would expect something else, like "prima ho finito un tema, poi sono andato a giocare" (first of all i've ended (wrote) the composition, then i went to play"... hope i was clear enough. ciao

/prima/ has two meanings: 1. before, 2. first at the feminime. /primo/ has the meaning of /first/. The two meanings of /prima/ might be the cause of confusion.