How long would it take after college to become either one of them?
and what shall be done in the process?
thank you for your help
Im in the process of changing my major so i can become a police detective/criminal investigator?
If you aren't already, make sure you go 4 years and get your Bachelor's degree as opposed to your Associates. From there, chances are slim to none that you will be hired in anywhere as a detective. Most departments, when they have a need for a detective, hire from within the department (ie a patrol officer). You would need to complete the academy and then get a job as a patrol officer for a police department (or sheriff's office). You'll have to put in your time and hopefully you'll be able to move up to Detective when the opportunity comes.
Im in the process of changing my major so i can become a police detective/criminal investigator?
No difference. Some departments call them one thing others call them something else.
It will probably take years as a uniformed officer before you become an investigator.