Module: small building blocks like oscillators, filters and envelopes.
Macro: between a module and an instrument in complexity, these are groupings of modules.
Instrument: a module that has a structure, handles MIDI, as well as its own snapshots and control panel. Instruments end in ".ism"
Ensemble: an instrument that contains other instruments. Ensembles end in ".ens"
Sequencer: either a module or an entire ensemble that allows one to program sound events on a timeline. The classic 16 step sequencer is common.
Drum Machine: A sequencer that triggers percussion sounds. There are also drum samplers which do not have sequencers attached, which the user can either trigger manually or through an external sequencer.
Sampler: either a module,instrument or ensemble that allows one to play recorded sound. There are many types of samplers which offer various editing, processing, or effects in addition to basic playback.
Synth: an instrument or ensemble which generates sound based on building blocks of simple sound waves. These sounds can be very complex. Some of the popular synthesis methods are subtractive, fm, and wavetable.
Sine Wave: a sound waveform which oscillates between y=n and y=-n.