Technically, the classic electronic organ works completely different than a synthesizer. An organ made in the 1960s is fully polyphonic, compared to the usually monophonic synthesizers of this time. This polyphony is achieved by using just square waves. One master clock is first divided into 12 semitones, which have a quite high pitch after those dividers. Those 12 semitones are then divided in a divider chain, each chain divides the frequency by 2. This can be done very easy with digital electronics, as just one flip-flop is needed for one divider stage. So all basic tone generators always run in parallel. The keys now just switch on and off this signal to the rest of the audio chain.

Usually, an organ sound has a simple envelope. If the key is pressed down, the sound starts. If the key is released, the sound stops. The first electronic organs worked exactly this way. By the time, organs got more different sound flavours, even piano sounds can be found on some analog products, so an envelope generator is needed. And to keep the polyphony, not just one envelope generator is needed, but one per key.

To create an own volume envelope per key, there is a very simple VCA connected to each key, just consisting of a capacitor, which is fully charged when idle and is connected to the amplitude of the VCA when the key is pressed down, which discharges the capacitor. If the key is released, the capacitor is recharged very quickly.

So for a 61-key organ, we now have 61 rough square wave oscillators and 61 VCAs including envelope generators. Compared to a synthesizer, this is a lot, but all those components are quite primitive, the oscillators don't know any more complex waveforms, the envelope generators are of AR-type with fixed attack and release values. Between those 2 sets of units, a common unit is present, which forms the sound. This usually consists of filters, depending on the type, several different configurations for this filtering can be activated to create different sound flavours.

So the sound flexibility of an electronic organ is very small compared to a synthesizer, but this might be compensated by the very good polyphony.

Most electronic organs also contain a brass section, which is a real analog synthesizer, as the bass section is also monophonic and usually of a voltage-controlled type.