so - such 

                  So       is used before an adjective or an adverb (so big,  so carefully)

                  Such,  followed by a or an, is used before an adjective+noun (.. such a long time)  

                                                     >   This book is so interesting.
                                                     >   This is such an interesting book.

                                                     >   Julie's new house is so big.
                                                     >   Julie has such a big house.
  

                                                     >   He drives so carefully.
                                                     >   He is such a careful driver.