What are the similarities and differences in the Lewis structures of $H_2SO_4$ and $SO_4^{2-}$?

(N/A) Similarity: In both structures,the central sulfur atom is surrounded by four oxygen atoms,and the total number of valence electrons involved in bonding and lone pairs is consistent with the octet rule or expanded octet requirements for sulfur.
Difference: $H_2SO_4$ is a neutral molecule where two hydrogen atoms are covalently bonded to two oxygen atoms. $SO_4^{2-}$ is an ion with a $-2$ charge,where the two hydrogen atoms have been removed as $H^+$,leaving their electrons behind on the oxygen atoms,resulting in two oxygen atoms carrying a formal negative charge.