What these two sonnets, 116 and 55 have in common is that they both speak about romantic Love. This can be seen in the last lines of sonnet 55: So, till the Judgement that yourself arise, /You live in this, and dwell in lovers’ eyes. And the middle of sonnet 116: Love's not Time's fool, though rosy lips and cheeks /Within his bending sickle's compass come.
They differ tho, in the fact that sonnet 116 speaks about Love in general, while sonnet 55 speaks about love for a particular person. Also, sonnet 55 speaks a lot about time, death and decay, and how and love and poetry overcome that.