[Python] In Sqlalchemy, what's different in defining table using Base and Table

I know i can define a table using Table:

user = Table('user', metadata,
Column('user_id', Integer, primary_key = True),
)


and using Base:

Base = declarative_base()
class User(Base):
__tablename__ = 'user'
user_id= Column(Integer, primary_key = True)


but what's the different???

Continue reading...