缩进不一样结果不同

wan = []
for a in range(1, 1000):
yue = []
for b in range(1, a):
if a % b == 0:
yue.append(b)
if a == sum(yue):
wan.append(a)
print(wan) # [6, 24, 28, 496]
wan = []
for a in range(1, 1000):
yue = []
for b in range(1, a):
if a % b == 0:
yue.append(b)
if a == sum(yue):
wan.append(a)
print(wan) # [6, 28, 496]
为什么这2个缩进不同会导致不同的结果，我是新手找不出原因，有老手来解答下吗