Many people think the XP-65 was superior to the 70, as it had a better range,
but it didn't have a seperate compression chamber and you had to screw/unscrew the reservoir, which caused the gun to start leaking after about 6 months of use.
There are at least two very different versions of the 65, the older one, which had a very good range, but used to break quickly and a reenforced second version that doesn't break quickly, but does not have the range of the older one.
The route of the water from the tank to the nozzle is a tube which goes to the end of this unsrewable water reservoir. The main problem about this is that the water-intake tube must be submerged in order for water to be fired, otherwise, you will only be firing only air or mist. Therefore the angles at which the weapon can be pointed and fired are limited.
This is why the XP-70 was equipped with a seperate compression chamber, which is its main advantage over the XP-65.
The 65 has many similarities to the SuperCharger 400, the unscrewable reservoir, the size and as far as I have heard the 400 has a similar range to the first version of the XP-65.