Albert and Elbert sound very much different to me. "Al" and "El" are pronounced as in "Alfred" versus "Elephant" - not even close in pronunciation (for me). BUT, some people called 'Elbert' will want it pronounced one way, and others another way.
Also, "Elbert" can be a first name as well as a surname.
I *think* 'Elbert' is an old version of 'Albert'. I'm not sure, though.