First off - if you're asking whether there is a difference between high-G and low-G tuning on an electric ukulele, the answer is obvious.
Low-G and High-G are definitely different.
As for different types of strings on electric, they DO make a big difference. In fact, electric pickups are probably even more sensitive to different string types than acoustic ukuleles. The sensitive pickups amplify the sound to high levels through amplifiers.
Furthermore, it is not all about the inherent "sound" of the strings. How the strings feel for the player is just as important.
My personal favourite strings for Risa ukuleles are D'addario Pro Arte Concert clear nylons or black nylons.
They give it a very crisp, full-sounding tone, while the tension feels great to play.
I am not a fan of the stock strings that come on the Risa. I believe they are fluorocarbons, Risa's own version of Worths.
Personally I feel like they are too much tension to feel comfortable for the way the Risa's are setup.
The Pro-Arte Tenor Clear nylons feel a bit too hard for me, so I prefer using the Concert strings, even on a Tenor ukulele.
Aquila are 'ok', but I'm not a fan of Aquila strings in general.
As for low-G on Risa sticks -
do not use wound strings on them!!. The plastic saddle cannot handle them - a metal wound string will chew into it.
As AL has stated above, unwound low-G strings work best - I have tried Aquila Red low-G and Worth Brown unwound low-G with success on the Risa.
Here is an old video of me playing a Risa with D'addario Pro-Arte clear nylons:
https://www.youtube.com/watch?v=tNIimZxy3iw
(note to AL: This is not the same Risa Tenor that I sold you. This is a different one that I owned before buying the one I sold you - I have owned multiple Risa sticks in my history)