以下兩句句子有什麼分別?

The first sentence refers to something happened in the past.
Say, Mary's mum passed away one year ago and she didn't tell Peter, so he didn't pay his last tribute to her mum. When he finally knew it and blamed Mary, Mary may say "the first sentence". That means she should have told him earlier, but she didn't.

The second sentence refers to something at the moment.
I'm sorry to tell you ... ( I'm going to tell you something.)
I'm sorry not to tell you.. (Something relates to present moment.)

Hope you can understand : )

１．我很抱歉沒有早些告訴你．
這是事後說的話，後悔沒有早一點說出真相．

２．我很抱歉沒有早些告訴你．
如果要把句２和句１分得更清楚，可把句２的譯為：我很抱歉因為我沒有早些告訴你．
比較：I'm (stupid) not to tell you earlier.
　　　我真笨，沒有早些告訴你．
在第二句，ｓｏｒｒｙ是說者的心情，如果把ｓｏｒｒｙ轉成不同的形容詞，會更容易明白．

第一句中，說者只是直接地說出他應該早點說出真相，第二句側是表達出說者對做錯決定而感到抱歉．