What is the difference between original sin and original guilt? This is a question that every convert to Eastern Orthodoxy always asked. The question can be stated differently: Does the Catholic doctrine of Original Sin include Original Guilt? Fr. John Romanides famously distinguish Ancestral Sin from St. Augustine's Original Sin, claiming the later was erroneously introducing Manichaean view of Original Guilt into Latin theology. Fr. Vladimir Moss wrote extensively to show why the doctrine of Original Sin is Apostolic in origin and dogmatically sound in Orthodoxy. To further clarify why original sin and ancestral sin are not substantially different? It's important to address what is the difference between Original Sin and later theological development from Protestant on Original Guilt?
There isn't a Catholic definition of guilt, therefore the Catholic understanding of guilt is how it is often understood:


  "That state of a moral agent which results from his commission of a
  crime or an offense wilfully or by consent" - cf. guilt (n.) | Online
  Etymology Dictionary.


There is a Catholic definition of sin:


  113. What is sin?
  Sin is an offense against God, by any thought, word, deed or omission against the law of God. - cf. re Article 10 of Apostle's Creed | Penny Catechism.


And of Original Sin:


  115. What is original sin?
  Original sin is that guilt and stain of sin which we inherit from Adam, who was the origin and head of all mankind. - cf. re Article 10 of Apostle's Creed | Penny Catechism.


In other words:

Original sin is that state resulting from the sin committed and stain of sin which we inherit from Adam, when he sinned by disobeying God's Commandment. Cf. (CCC 396-409).