Answer:
In health context, progression and variation are two principles of highly effective exercises.
So, the principle of progression is to continually increase the training intensity, pushing your boundaries more and more to achieve progress and ensure that you will be continuously growing over time.
On the other hand, variation is to change some aspect in your workout program to make your body face a whole new training stimulus. Variation is not about pushing up through your limits, it's about changing routines.
Therefore, the similarity between progression and variation is that they both are principles designed to improve your training, in order to achieve your fitness goals.
