We all make mistakes but what makes us different is how we respond after it. Both the devil and Adham (as) sinned, and Allah was angry with both of them. Adham and his wife (as) asked Allah for forgiveness. Allah was happy with them.
As for the devil he was asked to prostrate to Allah (swt) but he didn’t. He started to blame Allah for his misdeed and promised to misguide Adham and his children.
Allah tells us time and time again in the Quran “Do not give up, do not lose hope in my mercy, He is the most forgiving, the most merciful.”