However, you could use phrases to convey similar meanings depending on the context:
* For how something is similar or different: "identically" (meaning exactly the same), "differently" (meaning not the same), "similarly" (meaning in the same way).
* For how someone acts: "authentically" (meaning true to oneself), "consistently" (meaning always the same way).
Example:
* "The twins dress identically." (using an adverb to describe how they dress)
* "She behaved authentically, expressing her true feelings." (using an adverb to describe how she acted)
The specific adverb you choose will depend on the specific meaning you want to convey.