These sonnets by Shakespeare relate to the theme of love but Shakespeare, tired of the overly romantic view which people purport to support and which only complicates love, gives a down-to-earth view in both Sonnet 130 and Sonnet 138.
Sonnet 130 is surprising in its honesty but was never meant to offend. Inner beauty is far more precious than any external show and the pretence put forward by most lovers of their perfect partners is false and misleading, in his opinion. Sonnet 138 is similar in that it points out that lies often accompany relationships and the truth is often ignored - "I do believe her, though I know she lies."
However, in contrast to Sonnet 130, the lovers, aware of their own and each other's deceit, still pretend and "simple truth suppressed" allows them to continue in their tryst as "love’s best habit is in seeming trust." By pretending to trust each other, they are both satisfied and "in our faults by lies we flattered be."
By being blatantly honest in Sonnet 130, Shakespeare can recognize the inner beauty of his lover. She is a real woman, not false and "treads on the ground." Other poets "with false compare" but his love is "as rare/ As any she belied " and no amount of visions of "a goddess" would change that; never has he seen the perfect woman anyway.
Therefore, these poems are comparable because they both support the notion of truth but very different in their application of it to suit the poem itself.