Difference between accessing property methods and class fields (Objective-C)

Assume that I have this piece of code:

@interface Foo : NSObject {
    Bar *bar;
}

@property (retain, nonatomic) Bar *bar;

@end

When using this field/property, is there any difference between lines:

[self.bar doStuff];

and

[bar doStuff];

?

When doing assignment, property method will perform correct retaining, but what about the read access to the property, as described above? Is there any difference?