A short post here on some basic definitions in fitness training.
Contrast training (or concurrent training) is training that combines aerobic endurance and strength training in the same session. Either one can precede the other, and some examples include: skipping 30s during sets of bench press, or treadmill running in between sets of squats.
Complex training is training that combines power with resistance training. Oftentimes, the power component is in the form of plyometrics. For example, performing 5 * 42″ box jumps followed by heavy squat is an example of a complex training set. Another example is performing 3-5 plyometric pushups followed by dumbbell presses.
Both contrast and complex training are great training techniques, knowing when to use one however is the key to using them successfully!