Professional digital single lens reflex cameras offer more advanced features than entry- and mid-level DSLRs. The features will not improve pictures in any way from non-pro DSLRs. They will, however, make the process of taking pictures easier and faster and will withstand the heavy use demanded by pros.
Metal bodies: professional bodies are made of metal alloys, are very rugged and often shock-proof.
Built-in vertical grip: in general, professional DSLRs have a built-in vertical grip, making the body much larger but more convenient to use in a studio, for instance.
No built-in flash: The vast majority of professional bodies do not have a built-in flash, since most professionals will rely on an external flash at all times.
Burst rate: the burst rate and general operation speed of a professional body is unrivaled by other models. For instance, professional sports photographers always look for faster burst rates to make sure they are able to capture the action at all times.
Full frame: some professional bodies offer even larger sensors than regular DSLRs. These sensors, called “full frame,” offer more resolution and less noise. They are equivalent, in size, to 35 mm film. The viewfinder of a full-frame camera is extremely large and luminous.
Weather sealing: almost all professional DSLRs are weather sealed to some extent, in order to be used in the most difficult conditions.
Which type DSLR?
Only you can decide which level DSLR is best for you. Make a decision based on your current level of expertise and your current and future needs. Remember: the best camera is the one that you enjoy using, whatever its features list!