Hi! That's a good question actually. The reason why desktop has top 10 and mobile has top 5 is mainly because of the screen size. On desktop, you might have noticed the left panel with "New Chapters" and the right panel showing "Popular Manga." With limited room in between, only 5 manga can fit comfortably. Also, to keep things neat and easy to use, the horizontal scroll (left to right) is not added because it's not the conventional way to interact with a computer.
On the flip side, mobile devices use touchscreens, which is a convenient way to swipe through content horizontally. This is more "natural" and it makes it intuitive to scroll through the featured mangas.
As for the different set of mangas featured, it's to diversify the mangas featured and encourage users to explore more titles. Notice how doujinshi is removed but more genres are also added on main page? It's so that mggo wont be a yaoi dominated site. I know this is a different topic lol but it's on the same objective to diversify the content on mggo
TL;DR:
- Desktop version has top 5 mangas because of limited space
- Mobile version has top 10 mangas because of touchscreens
- Different sets of featured mangas is to diversify content
I hope this answers your question
Why is the desktop version different than the mobile. In the mobile it has top 10 manga and on desktop it top 5 and both versions have different mangas featured.