Posted from TSR Mobile
I'm just about to commence my MSc in Criminal Justice and Criminology. The two are different, but do interlink. It is likely that whichever you choose, they will share content from the other.
Criminology is the study of crime, looking at why people commit crime and how society responds. Criminology is all about asking questions and obtaining information with the aim of proposing how crime can be prevented in the future. There is a lot of analysing information and researching that criminologists undertake.
Criminal Justice is concentrated more on systems associated with crime, for instance, police, courts, probation, etc and often covers the powers and limitations of these agencies. Law makes up a big proportion of study on a Criminal Justice programme.
I hope this helps.