Tony hates Bobby for several reasons:
even though he was the son of Johnny Boy Soprano had to gain experience by killing Willie Overall, and doing the robbery, during a game of cards;
1) Bobby is one of the few characters with Johnny Sack that does not have mistresses and deeply loves his wife;
2) Bobby has children who love him, while Anthony Jr. hates him, Meadowlooks at him from top to bottom and Carmela, is with him, just for the money;
3) Bobby became a soldier and then captain, very easily as Tony, but Tony the envy his happiness