Longhorn cheese is a type of mild Colby cheese cut into a half
circle shape.
Colby jack cheese is a combination of two different cheeses. It
is made up of Colby (a yellow cheese) and Jack cheese (a mild,
white cheese). It is usually cut in a brick style.
Thus, the differences are::
1. Longhorn is all one cheese; Colby Jack is a combination of
two cheeses.
2. The two cheeses are cut differently.
3. Flavor/taste
4. Color--Longhorn is uniform; Colby Jack is mottled orange and
white.