So put simply, Cyber Security is a very broad term that covers many areas. Think of Cyber Security as the Sea with many different types of fish. Forensics is an area within Cyber security, or 1 type of fish in the Sea.
Cyber Security includes things like, Application Security, Identity & Access Management, Mobile Security, Incident and Vulnerability Management, just to name a few.
Personally, I can speak to both. I have a Cyber Security job in which I have done and do some of the things mentioned above. Also, I have a degree in Digital Forensics. Digital Forensics is very specific, you would investigate cases and recover digital evidence, analyze incident, etc. So they are not exactly the same thing.
If you love science and technology, definitely look into Forensic Technology.
I hope this helps.