No suffix=Japan, Z=US/Asia(excluding Japan), E=UK, H=Europe, ZR=Russia
There are other suffixes but I don't know much about them. They refer to regional requirements such as power cord, power consumption rating, and language used on the carton and in the manual. Japan uses Japanese writing on the unit itself when everywhere else uses English.
The tuners probably have the most variation.
UK/Europe refers to AM as medium wave (MW)
UK/Europe has one shortwave band (5.95-18MHz) and one longwave (LW) band: 150-285KHz (148.5-285 in Europe)
Everywhere else has two shortwave bands (SW1=2.3-7.3MHz, SW2 =7.3-22MHz), but no longwave.
UK AM intermediate frequency (IF) is 465-468KHz, but everywhere else it's 455KHz
FM in Russia is 64-77MHz, Japan is 76-108MHz, and everywhere else it's 88-108MHz