These poems both share a common theme of black experience in the United States, and in both poems, there is evidence that the speaker has suffered racism. Wheatley refers to the "scornful" looks she has received from those who view her blackness as a "diabolic die," and Hughes laments being sent "to eat in the kitchen / When company comes." Both speakers have been mistreated because of the color of their skin.
The tone in Hughes' poem, however, is radically different to that in Wheatley's. If "tone" represents the author's attitude towards their subject, then it is fair to say that Wheatley's attitude towards her own blackness is different from Hughes'. Wheatley describes being brought from her "pagan land" with an element of religious gratitude: her "benighted soul" has been educated by white people about God and redemption. Certainly, she pleads for compassion from Christians towards those who, "black as Cain," have simply been uneducated about the potential of joining the "angelic train" of Christianity. However, there is a sense that the speaker has had to be "refin'd" first: the word "benighted" is particularly telling, as it unites blackness with connotations of ignorance and spiritual darkness. Wheatley expresses gratitude to those who have helped her move beyond her "benighted" African self and become, as it were, civilized.
Hughes' poem, on the other hand, is a plea for equality. Rather than allowing that there is a negative connotation to blackness, he repeats that "I, too, sing America." There is no equivocation here: Hughes is claiming the equal place which should be afforded to him, and yet is denied to him on the basis of racism. Rather than being grateful for what he has and content with his lot, he looks towards a brighter future when "they'll see how beautiful I am / And be ashamed." White people, in Hughes' eyes, should recognize that black people are their equals in every way, and that their blackness is not a failing or a curse for them to be rescued from, but beautiful in its own right. Hughes' blackness, unlike Wheatley's, does not need to be "refin'd."