第1组的两个句子,个人觉得是一样的,只不过第一句中的after是连词,省略了与主句相同的主语与be动词,第二句的after是介词.两句都可以这样补充：
a.After(she was) interviewed for the job,She felt disappointed.
b.After being interviewed for the job,She felt disappointed.
第二组就不同了,主语不一样.
a.If writing neatly,you may get a higher mark.
b.Written neatly,the letter will be easier to be read.