Screenshot Resolution issues

I have an iPhone 6 and an iPad Air (1st gen). There is an app I use on both devices from which I need to take screenshots. The quality of the screenshots taken on the iPhone is significantly better than those from the iPad. Why is this? Is there any way to fix this issue?

The reason why it matters to me is that the iPad has a larger surface area and therefore shows more of the particular thing I need to take the screenshot from. If I can't fix the resolution problem then it means I'm stuck with doing it on the iPhone which essentially doubles the amount of work because it shows less of the item.

Help and advice are appreciated. Thanks.