A hacker is a person who is proficient with computers and/or programming to an elite level where they know all of the in’s and out’s of a system. There is NO illegality involved with being a hacker.
A cracker is a hacker who uses their proficiency for personal gains outside of the law. EX: stealing data, changing bank accounts, distributing viruses etc.
What the hacker does with their knowledge of systems within the definition of the law is what defines them as a hacker vs a cracker. It’s then safe to say that all crackers are hackers, but not all hackers are crackers. This is an important distinction.
A hacker is a person who is very proficient and experienced in how computers work.
Cracking is hacking with criminal intent.