If you haven't ridden your current bike very much, then ride it. Ride it a lot. Till you know what it does or doesn't do for you. Then get another bike that solves some of those things that the old bike can't.

Personally, I'm not certain what the new bike will solve that the old bike can't do. But I may not have compared the same models you are talking about.

Realize also that a mountain bike is generally made for where only mountain goats can go. Off of the paved or gravel road. That's why they got the name mountain bike. Road bikes work every bit as well on mountain roads. Paved or gravel.