SO - SUCH

SO and SUCH often have the same meaning : 'very' or 'to this degree'.

So is used before an adjective or an adverb (without a noun after it):

• so big
• so carefully

Such is followed by 'a' or 'an', + an adjective + a singular noun : 

• such a long time
• such an incredible story

Such is used without a, an before plural nouns, mass nouns (luggage, furniture)
and abstract nouns (advice, courage, generosity, kindness ... )

• such fools
• such (beautiful) furniture
• such generosity

Compare the following sentences:

• This book is so interesting.
• This is such an interesting book.
• Such interesting books are hard to find.
• I was amazed that the crowd was so big.
• I was amazed that there was such a big crowd.
• Such big crowds can be frightening.
• The story was so complicated.
• It was such a complicated story.
• Such complicated stories are difficult to follow.
• You are so intelligent.
• You are such an intelligent person.
• A person of such intelligence is a pleasure to meet.

So ... that and such ... that are used to describe reasons and results.

So + adjective + that :
◊ The hotel was so comfortable that we decided to stay another night. 

Such + adjective + noun + that :
◊ It's such a comfortable hotel that we'll definitely stay there again.