there are over 120 variants and
it does not only come in the 9mm.
(well the US is an exception)
There are also the 10mm and .40S&W models. They are called MP5/10 and MP5/40. The newest model of the MP5 would be the MP5F which stands for french and is being developed specifically for the French LE. But the newest MP5 model that is distributed world wide is the MP5K/PDW(even though it was made specifically for the US). there are many and i mean many trigger groups for the mp5. Few examples are, SEF: Safe, sEmi, Full-auto. 0-1-2: safe, semi, 2rd burst. 0-1-3: safe, semi, 3rd burst. Navy: which is just the SEF trigger grouping, safe semi full-auto
The precursr to the MP10 and MP7 SMGs.