According to the specification the M1 has a maximum reach distance of 20 km, while the M3 just 10km. Interesting that they have the same battery capacity and same power...maybe is just an error in the description!
The theoretical minimum age is 8 years. But that's just a recommendation, because you might not be able to control it properly before that. But I think if you can do it at 7, you can do it. There are no direct regulations or minimum ages.