when you compare them; in comparison
Used to introduce an observation made after placing things side by side or comparing them directly. Often appears at the beginning of a sentence.
When you compare the two photos side by side, the differences become clear.
When you compare it with last year's data, you can see that sales have increased.
A set phrase composed of the te-form of 並べる (to line up) + 見る (to see) + conditional と, literally 'when you line them up and look'.