Chapter 1 of this book describes the first theft of which Silas is falsely accused in Lantern Yard. The impact of this false accusation, and the treachery of his friend William, is of course the trigger that sends him away from Lantern Yard and to Raveloe. He has lost such faith in humanity and in religion that he spends the rest of his life, up until the second robbery he experiences, in isolation and quietly hoarding gold:
So, year after year, Silas Marner had lived in this solitude, his guineas rising in the iron pot, and his life narrowing and hardening itself more and more into a mere pulsation of desire and satisfaction that had no relation to any other being.
The life of Silas becomes defined by solitude and avarice alone. The first robbery was one that he was accused of, though he did not commit it. The second robbery is one that he himself suffers, as it is his gold this time that is taken. However, it is clear that the impact of this robbery is massively different. Far from forcing him to withdraw from society and become isolated, as the first robbery caused him to do, the second robbery actually makes him dependent on society and helps him to interact and move towards being accepted by Raveloe, as Chapter 7 makes clear:
The strangely novel situation of opening his trouble to his Raveloe neighbours, of sitting in the warmth of a hearth not his own, and feeling the presence of faces and voices which were his nearest promise of help, had doubtless its influence on Marner, in spite of his passionate preoccupation with his loss.
So, considering the two robberies, the first is different from the second in that it drives Silas away from humans, whereas the second drives him into community with humans, which he has done his best to remain isolated from.