Why append to list is not the same as +=

The first method uses list comprehension, and appends the string in the array 'names' satisfying the given criteria.

First code>
Code:names=['Jerry', 'Kramer', 'Elaine', 'George', 'Newman']
best_list = [name for name in names if len(name)>=6]
print(best_list)Output:
Code:['Kramer', 'Elaine', 'George', 'Newman']----------------------------------------------------------------------
The second method also does the same, as above.

Second code>
Code:names=['Jerry', 'Kramer', 'Elaine', 'George', 'Newman']
better_list=[]
for name in names:
if len(name)>5:
better_list.append(name)
print(better_list)Output:
Code:['Kramer', 'Elaine', 'George', 'Newman']----------------------------------------------------------------------------------
If change the second code to the one below, then the individual characters, are stored:

Third code>
Code:names=['Jerry', 'Kramer', 'Elaine', 'George', 'Newman']
better_list=[]
for name in names:
if len(name)>5:
better_list+=name
print(better_list)Output:
Code:['K', 'r', 'a', 'm', 'e', 'r', 'E', 'l', 'a', 'i', 'n', 'e', 'G', 'e', 'o', 'r', 'g', 'e', 'N', 'e', 'w', 'm', 'a', 'n']-----------------------------------------------------------------------------------------------------
Question: a) Why the third code, saves the individual characters, is unclear.
b) Also, how can the first code be modified to give the same output as the third code?