It's all really quite straightforward. Whatever the other person is using to play and score lower than me is obviously the easier platform to play. ;-)
I've also read that there are some country clubs that won't allow people on mobile platforms to join. But part of that may be due to specific additional software they want their members to use during play or to the fact that cross-platform play is not supported by WGT.
Regardless, I've read where some believe the mobile platform (esp. iPad) is easier to play. But I've also read where some see it as more difficult. Here's my take on it from reading forum posts over the last year:
- Putting: The PC version seems a bit easier because it provides you with better grid information than the mobile platform.
- Approach shots: The iPad or mobile version may be more forgiving.
- Hitting the ding: The PC version seems easier to ding your shot. (But see above regarding forgiveness).
Personally, I think it's a push with neither venue being overall easier. And let's remember that there's probably a bit of "baby duck" syndrome going on here. Whatever one learns first, the person is most likely to be partial to that version.
And the other thing to remember is that there is a wide variance of the PC equipment that people use. With a PC, a person could really max out their equipment and most likely make the game a bit easier, if they chose to do so. As just one example, think of the size of screens that are available for PC users. So the comparisons become complicated quite quickly.
That's my take. Others may see it differently.