Tra vs. fra
In Italian, the prepositions tra and fra are synonyms and are almost always interchangeable. They both translate to between, among, or in when referring to time. The primary difference between them is not in meaning but in euphony, or how they sound in a sentence.
Tra
A1The preposition tra means between two entities, among a group, or in for a future time period. It is generally interchangeable with fra, but it is stylistically preferred when the following word begins with the letters fr- to avoid the repetitive fra fr... sound.
La mia casa si trova tra la scuola e il parco.
(My house is located between the school and the park.)
Il treno parte tra venti minuti.
(The train leaves in twenty minutes.)
C'è un grande legame tra fratelli.
(There is a great bond between brothers.)
Puoi scegliere tra queste tre opzioni.
(You can choose among these three options.)
Tra dire e il fare c'è di mezzo il mare.
(Between saying and doing, there is a sea in the middle. (Italian proverb))
Fra
A1The preposition fra also means between, among, or in for a future time period. Its usage is identical to tra, but it is the preferred choice when the word that follows starts with tr- to avoid the awkward tra tr... sound.
L'appuntamento è fissato fra tre giorni.
(The appointment is set for three days from now.)
Fra poco inizierà il film.
(The movie will start in a little while.)
È difficile trovare parcheggio fra queste strade strette.
(It is difficult to find parking among these narrow streets.)
Dividi la torta fra tutti i bambini.
(Divide the cake among all the children.)
Fra me e te, non credo che sia una buona idea.
(Between you and me, I don't think it's a good idea.)
Summary
Essentially, tra and fra are interchangeable synonyms. The only practical rule governing their use is to avoid cacophony (a harsh sound). Use fra before a word starting with tr- (e.g., fra tre) and use tra before a word starting with fr- (e.g., tra fratelli). In all other contexts, the choice between tra and fra is purely a matter of personal preference.