Is sino just a more formal form of pero?

Question

Or are there different meanings and whatnot? We were never really 'taught' sino but it pops up in a lot of our material lately.

Answer 1

Check out this lesson:

3.15 - Prepositions A, Pero, Sino, & Sino Que Go on Vacation

Go to

*** Learn Spanish**,up there on the left just under "SpanishDict"  

``and open the Lessons 3 section. It's near the bottom. Enjoy

Answer 2

Basically, "pero" is used to indicate an exception to a positive statement and "sino" for an exception to a negative statement.

P.S. The are not interchangeable.