Hackers and crackers are the software programmers who use dubious ways to get control over your computer and systems. The intent of both hackers and crackers is to gain control over your computer so that they can get sensitive confidential information.
They then use this information against you by stealing money, personal data, pictures, bank details and government military information, so on and so forth. This information can either be sold for money or hackers access the account themselves to rob you directly.
Originally hackers were the gifted programmers who gain access to the systems or network to showcase the security loopholes to the administrators. Later the term cracker was coined for such activists who had intentions of doing malicious activities. Crackers have an end goal of destroying data and networks for personal monetary gains.