Hobby vs. passatempo
While both 'hobby' and 'passatempo' refer to leisure activities in Italian, they have subtle differences in usage and connotation.
Hobby
'Hobby' in Italian is a loanword from English and refers to a regular activity done for pleasure, often involving skill or expertise.
Il suo hobby è la fotografia.
(His hobby is photography.)
Collezionare francobolli è un hobby costoso.
(Collecting stamps is an expensive hobby.)
Passatempo
'Passatempo' is a more general term for any activity that helps pass the time pleasantly, not necessarily requiring special skills.
Guardare la TV è il suo passatempo preferito.
(Watching TV is his favorite pastime.)
I giochi da tavolo sono un ottimo passatempo per le serate in famiglia.
(Board games are a great pastime for family evenings.)
Summary
While 'hobby' implies a more serious, regular engagement often involving skill development, 'passatempo' is broader and can include casual activities simply meant to occupy time enjoyably. 'Hobby' is often used for more structured activities, while 'passatempo' can encompass both casual and structured leisure pursuits.