If there is no great or small sin why did the sin commited by the devil make him liable to eternal damnation?

Most Christian denominations teach that the devil and his angels cannot be forgiven because they committed an **eternal sin**, while Adam and Eve committed a **mortal sin**, hence they can be forgiven. How did the devil and his angels end up committing an eternal sin when the only sin that leads to eternal damnation is **blasphemy against the Holy Spirit** All **sin** can be defined as going against the **will of God in heaven or on earth** Was it **pride** that made the devil and his angels liable of eternal damnation and how is this a tresspass against the Holy Spirit? Since the Bible claims that **no sin is small or great**, why was the sin by the devil and his angels so great that it made them guilty of eternal damnation and how is the sin of pride any different from the sins committed by men because even men have pride and conspired to be like God in the Tower of Babel?