The probes on the 733 are called hybrid probes and can be used for either meat or chamber temperatures. The screen on the 733 may be bigger, but the temp section of the display is just as big as the 732.
The probes that come with either the 732 or 733 are only 3 feet long. They work fine but are too short IMO. The replacement probes are 6 feet long and give you much more versatility. Replacement probes run about $15-$20 each on average.
I don't own the 733. I have the 732. I have two each of the longer replacement chamber and meat probes and use them exclusively. I have them labeled at the transmitting unit connector end "chamber top, chamber bottom, meat top, meat bottom" and just switch them out while cooking to check temps when my WSM is fully loaded. If done quickly you don't lose the connection with the receiving unit. It was cheaper doing it like that than buying two Mavericks.
The prices on all the 732s and their replacement probes have come down quite a bit since the 733 was introduced. I guess it just depends how much money you want to spend. I only use my 732 for monitoring temps. I never use any of the other fancy features like alarms. They just eat up the batteries.