The term "nonisomorphic" means "not having the same form" and is used in many branches of mathematics to identify mathematical objects which are structurally distinct.
Objects which have the same structural form are said to be isomorphic.
Nonisomorphic
See also
Isomorphic, IsomorphismExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Nonisomorphic." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/Nonisomorphic.html