Comparing side-by-side circumvents our cognitive limits

Comparing two things are easier when what you're comparing are visible. There's a tendency for software engineers to flip their windows or screens very rapidly to compare two things and most often they can't spot the difference (Change blindness).

When windows or screens are rapidly switched, what you're doing is you're committing the details into your working memory, we have Working memory limits, and which make Cognitive load higher.

Rather than using your working memory, put them side by side instead. This may increase your Perceptual load. This is great, because Distraction has low impact on tasks with high perceptual load.