What is a major difference between the fifth and fourteenth amendments' due process clauses?

The major difference is that the Fifth Amendment's due process clause originally applied only to the Federal Government.

The Fourteenth Amendment states  "(…) nor shall any state deprive any person of life, liberty, or property, without due process of law; nor deny any person within its jurisdiction the equal protection of the laws."

Due process deals with the administration of justice so that the due process clause is a safeguard from arbitrary denial of life, liberty, or property by the government outside the sanction of law.