Not sure if this is a platform bug or by design feature with case insensitive variable names?, but it gave me a lot of trouble so wanted to post a question about it to document the workaround I found.
GeoCodeCensusResponse geoCodeCensusResponse = (GeoCodeCensusResponse)System.JSON.deserialize(reponseBody, GeoCodeCensusResponse.class);
system.debug(geoCodeCensusResponse);
The above code will not compile with the following error: "Variable does not exist: GeoCodeCensusResponse.class"
Only after changing the variable name am I able to save. My fix looks like the following.. changing my variable name to "test":
GeoCodeCensusResponse test = (GeoCodeCensusResponse)System.JSON.deserialize(reponseBody, GeoCodeCensusResponse.class);
system.debug(test);