Differentiate, please.

My brother who lives in Italy is a teacher.

You probably have more than one brother. Without the commas, it tells the reader which of your brothers you are talking about. (Not the brother who lives in the US, nor the one who lives in Canada.) This is a restrictive clause and gives the reader necessary information to property identify who you mean.

My brother

Oh yeaaah! I didn't see it that way very closely. Thank you very much, Grammar Geek.

Please, can you anyone tell me the difference between laugh and giggle?

Could anyone give the difference between

"one-on-one" and "one-to-one" ?

I will be interviewed by a teacher for a course I have applied. In my email, I asked if it will be a one-on-one interview or a panel interview. He replied to me, "It will be a one-to-one interview."

Thanking in advance the people who will be replying.

In that context, there's no difference. You will not have a panel interview, when three or more people ask you questions at the same time. You'll talk to one person at a time.

As for your other question, a giggle is a type of laugh. It's often considered "girlish" and I wouldn't write "The lumberjacks sat at the bar, giggling over their beer."

Hi G,

Sounds like you are not familiar with the Monty Python sketch and song called 'I'm a lumberjack'.

Here are the lyrics.

I'm a lumberjack, and I'm okay.
I sleep all night and I work all day.

MOUNTIES:
He's a lumberjack, and he's okay.
He sleeps all night and he works all day.

BARBER:
I cut down trees. I eat my lunch.
I go

Oh, my yes. I've sung it many times, though I usually get the lyrics wrong about the time I get to the verse where they dress in women's clothing.

Will you join me in a chorus of Philosophers' Song too?