field symbol assigning a table type

hi

i dont understand creating a data object with create data type ref to and assigning the same to fieldsymbol?i can create a internal table type and using assign statement i can assign it to fieldsymbol but what is the advantage of assigning the same using type ref to :

1)

2)

DATA: <lfs> TYPE ANY TABLE.

data: it_table type table of ty_table.

assign (it_table) to <lfs>.

what is the difference between the above two types of assignments?

i am unable to figure out which is better and why...