Act 4, Scene 2 of Shakespeare's Macbeth provides an excellent example of the difference between pathos and tragedy. The incident involving the murders of Lady Macduff and her son create sympathy, pity and compassion on the part of the audience for the two victims as well as Macduff. This is pathos.
Tragedy, on the other hand, involves a tragic flaw on the part of the "victim." Macbeth, for instance, is a slave to his ambition. When he is killed he is the cause of his own downfall. Some flaw contributes to the downfall of a tragic protagonist. It may or may not create sympathy, etc., as Hamlet's death may in Hamlet, but either way something about the tragic figure contributes to his fall.
This is not the case in pathos. Lady Macduff and her son do nothing to contribute to their murders.