Such and So - what is the difference?

Such + (adjective +) noun
'Such' is a determiner, which means it is used before nouns. The noun can be preceded by an adjective, but it does not always have to.
So+ adjective
'So' is an adverb, and is used to modify adjectives.

Here are a few examples:

such + (adjective +) noun	so + adjective
Those are such good chocolates.	Those chocolates are so good.
She is such a great cook.	She is so good at cooking.
He’s such a kind person.	He is so kind.
They are such snobs.	They are so snobbish.
Those are such cool shoes.	Those shoes are so cool.
November was such a cold month.	November was so cold.
This is such a wonderful kitchen!	This kitchen is so wonderful!
Thank you. You are such a kind person.	Thank you. You’re so kind.
That was such an unpleasant experience.	That was so unpleasant.
It was such a hot day we couldn’t work.	It was so hot we couldn’t work.
She is always such an elegant woman.	She always dresses so elegantly.

"So" is used to emphasize the adjective. It is so tasty that you are it all, or he was so kind that he helped you when you did not expect him.
As mentioned earlier, it is an adverb, just like 'very', so it can be used with adjectives (so nice) and adverbs (so quickly). But you cannot use it in front of nouns (so idiot, so school).
If you want to say about someone that they are an idiot, you use such (He is such an idiot!). And you can also describe the school, again with such (This is such a large school.)

When you use "such", it is followed by a noun, so make sure you use "a/an" when there is a countable one:

such a snob, such a tasty meal, such a good mood;
unlike uncountable nouns and plurals:
such beautiful views, such tasty meals, such tasty bread, such rubbish.