The way I look at it is like this
Interventional Cardiologist = Surgeon
Noninvertentional Cardiologists = subspecialized IM docs
This is a very loose interpretation but it should give you an idea about the differences between the two. Interventional cardiologists almost exclusively focus on procedures and perform a lot of them much like a surgeon. Usually the non-invernetional cardiologists in the group will do the follow-up and office consultation.
Yes, Interventional Cardiologists can work drastic hours and have a very surgeon-like lifestyle. The upside is the money. The cardiologists that you hear of who earn 7 figures or close to 7 figures are often interventional cardiologists. Please understand, however, that these interventional cardiologists are working really hard to earn those 7 figures as they are busy performing many procedures per day and willing to get up at all odd times of the night to do so.
Most people who go into interventional cardiology vs. non-interventional has little if anything to do with money. The nature of the work is very procedural and thus people who enjoy procedures and less patient contact love this field. While many cardiologists who prefer a more regular work schedule and enjoy interacting with patients choose the non-interventional route.
Funniest thing I 've heard in a LONG time 
