В чем разница между ".append ()" и "+ = []" в Python?

Question

В чем разница между:

some_list1 = []
some_list1.append("something")

и

some_list2 = []
some_list2 += ["something"]

Answer 1

давайте сначала рассмотрим пример

list1=[1,2,3,4]
list2=list1     (that means they points to same object)

if we do 
list1=list1+[5]    it will create a new object of list
print(list1)       output [1,2,3,4,5] 
print(list2)       output [1,2,3,4]

but if we append  then 
list1.append(5)     no new object of list created
print(list1)       output [1,2,3,4,5] 
print(list2)       output [1,2,3,4,5]

extend(list) also do the same work as append it just append a list instead of a 
single variable