The best comparison of the rhetorical devices used in the passages is:
What to the Slave is the Fourth of July employs rhetorical questions and Lincoln’s Second Inaugural uses anaphora.
In Douglass's speech, he uses rhetorical questions to provoke thought about the hypocrisy of the Fourth of July for enslaved people. In contrast, Lincoln's address uses anaphora, as seen in the repeated phrases such as "with malice toward none" and "with charity for all," to emphasize his call for unity and healing in a nation divided by war.