Can anyone help to explain why sample/LoginInfo.* code in this way?

[drinking]

//LoginInfo.h
@interface LoginInfo : NSObject{
@private
    NSString *_password;
    NSString *_login;
}
@property(strong) NSString *login;
@property(strong) NSString *password;

@end
//LoginInfo.m
@implementation LoginInfo
@synthesize login=_login;
@synthesize password=_password;
@end

what's the difference between just coding like this

@interface LoginInfo : NSObject{
    NSString *password;
    NSString *login;
}
@property(strong) NSString *login;
@property(strong) NSString *password;