How is sonnet 55 and sonnet 43 alike?

They are both sonnets, and Shakespearean sonnets. They are both addressed to someone described as "you". They are both, to a certain extent, praises of the person to whom they are addressed. Sonnet 55 uses the phrase "But you shall shine more bright" which echoes the primary image of Sonnet 43, as seen in the line "thy much clearer light".