Direct Observation Unit VS Telemetry Unit VS StepDown

I recently got hired as a nurse extern. My manager gave me a choice of what unit I would like to work at. I would love to work with patients having cardiovascular system-related problems. I basically prefer to work at a telemetry unit, but not in an intensive cardiac care floor. However, lately, I was confused as to what is the difference between telemetry unit, direct observation unit (DOU), and a step-down unit. I know a telemetry unit is the "Step-down" the ICU. Nonetheless, it seems to me that DOU and telemetry are the same. Or are they different? If they are different, what is there difference? Which is a better place to work at, at a tele floor or at DOU? Which one is busier? Can you please shed some light on these. Thanks peeps!
My experience is that an observation unit is in between a CCU and stepdown unit where you have certain types of cardiac patients like those who have unstable angina or are post cath and so on who require closer monitoring than is given on a stepdown unit. The stepdown unit, I feel, is a unit that normally gets patients from either the intensive care unit or observation unit. My experience is that in a ICU/CCU situation you provide more intensive care, observation is less intensive care, and stepdown gets the patient ready to be discharged.