One difference I've noticed is that on the mandolin, I tend to look at my fretting hand. On the violin, I tend to look at the bow - and watch my fretting hand with my ears
I'm not sure which is more difficult, but I'm finding that with each instrument, I need to approach it as a 'total beginner' and build technique at my own pace. Each require sound fundamentals to get the best tone possible.
And now for today's weather....sunny, with a chance of legs
"Give me six hours to chop down a tree and I will spend the first four sharpening the axe." - Abraham Lincoln