iOS initWithFrame:frame] 与 [UIButton buttonWithType] 对比

What's the difference between the following two code snippets?

1.

UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
    button.frame = frame;

2.

UIButton *button = [[[UIButton alloc] initWithFrame:frame] autorelease];

-buttonWithType:
UIButton
+[NSObject alloc]
0
buttonType
0
UIButtonTypeCustom
-buttonWithType:
buttonType
UIButtonTypeCustom
1
0
-initWithFrame
UIButton
+buttonWithType
+alloc
-initWithFrame:
buttonType
buttonType