Though both BJTs and FETs are Transistors that can be used as amplifiers (or switches of course), that is just about everything they have in common. Their operation is very different.
Transistors: (Download my Transistor Theory PDF) They are current-controlled devices. This means that the amount of current that flows through the Collector-Emitter is controlled by the amount of current which flows through the Base.
FET: They are voltage-controlled devices. In principle, no current flows through the base (other than a few micro amperes due some manufacturing parameters). The amount of current which flows through the Drain-Source is controlled by the voltage applied at the Gate.
I stumbled upon two animations with hydraulic equivalents of a Transistor and a FET device. Watch them and notice how the current flow is controlled in each case. Very good work!
The Bipolar Junction Transistor (BJT) Hydraulic Equivalent Animation
Please let me congratulate you for the transistor animations. Although they're very suggestive, the video length is short and I had to replayed it several times. Also I downloaded the Transistors Theory PDF and due to the analogy to the hydraulic system, I have a better grasp on transistors now. Keep up the good work.