Pressurised thrusters - if all of the fuel storages are 100% - 95% the thruster gets ~25% bonus power. If there is less than 95% fuel left, power drops to 100% - ~25% when on the brink of running out of fuel. For more clearity i attached some numbers. More fuel - more power
Hybrid thrusters - they are very fuel efficient, but uses energy. Fuel to energy alternative
Ion thrusters - 2x2 sized thrusters that have the same amount of thrust, but uses energy instead of fuel. Large energy thrusters
Overclocked thrusters - have 30 % more power, but use 50% more fuel and act as heaters: one thruster begins to melt in 8 seconds of continuous firing. Unreliable, but powerful thrusters
Clockwork thrusters - Works in bursts ( they work for random periods between 0.1 and 0.6 seconds and then even if the key is pressed they turn off ). If being used while not off they quickly generate heat. But if timed perfectly they have 20 % more power. Consumes same amount of fuel. Better timing - more power
Tweaked thrusters - produce 20 % less thrust and take up 1x3 space, but consumes 50 % less fuel. Highly efficient
Eco thrusters - Consumes no fuel, and consumes only 10 % of energy equivalent, produces 15% of normal thrust. Almost free but weak
Turbines - thrusters that use energy instead of fuel, and loose power if they go above a certain altitude ( too rare atmosphere ), and can be more powerful when in dense atmosphere, or less powerful when in less dense atmosphere. Power depends of atmosphere density and altitude
Independant thruster - a small thruster with a small fuel tank attached to it. Behaves just like one and the other, only that it has fuel storage, which is by default full, and the efficiency is between small and normal thruster. A bit weaker thruster with fuel storage. sorry, no drawing...
And for no other reason than, becouse i could, i have drawn some examples of almost usable quality.