Different Ways for creation of active record object

Rails Allows Programmer to create active record object using following 

Ways

1)user=User.new(:name => "David", :occupation => "Code Artist")

2)

user = User.new do |u|
  u.name = "David"
  u.occupation = "Code Artist"
end

3)user = User.new
user.name = "David"
user.occupation = "Code Artist"