what's the difference between “favourite” and "popular"

FAVOURITE is used to describe something that you like most of all. Something preferred above all others. For example "My favourite book is "War and Piece".
POPULAR is used to describe something that a lot of people like. For example "Rugby is popular in Australia". This means that a lot of people in Australia like this sport.
You can also say "popular WITH (somebody)" : This resort is popular with tourists. This means that a lot of tourists like and visit this resort. But "popular AMONG" is also correct although less common.
You can also use favourite as a noun: "That movie is a great favorite with audiences everywhere". "Of all his books, do you have a favorite?"
I hope this was useful )

Thank you very much! You are really helpful. However, can I say "Canberra has become a center of education and a favourite place for tourists"?

Is there a phrase like "be popular for sth.", and if so, what does it mean?

I think it's possible to say "favourite for" (maybe it's not so common) :
Australia is still one of the favourite destinations for Chinese travellers.
Thailand is the most popular destination for Britons.
You can also say ¨a popular place with tourists¨ or simply "a popular tourist destination".
"popular for something" ? Well... you could use it in a sentence like this:
"Reality television is a popular medium for the broadcast of American culture". ( when you talk about the purpose - "a popular medium which is used for..." )

We don't say "popular for"...(something. We could say "popular because of"......something.

Phones Credit Cards Most Popular For Thieves

Reclaimed teak is popular for outdoor furniture

Chunky Monkey's Seafood Market popular for fresh San Antonio Bay seafood

Elderberry clusters popular for wines

Online learning increasingly popular for doctors

Having had cool Spring weather so far this year, it's no surprise to see that the Mediterranean is proving popular for the region's travellers once again

Nepal locations popular for foreign film shoots

Oh yes. A slightly different meaning. I never thought of that.