Short answer: no

There is no difference in meaning.

Long answer: just a little bit, with an ambiguity

1. One of the meanings of rise that applies to an immobile, unchanging physical object (like a hillside) is to extend from ground level upward.

2. That's also one of the meanings of the phrasal verb rise up in the same context.

3. Ahead of in this context means in front of you, or that you are traveling toward the hillsides. It doesn't suggest anything about the distance to the hillsides.

4. Up ahead of is a phrasal preposition that means the same thing, but usually suggesting that the object of the preposition is not far ahead.

So, a listener could hear the sentence as rising up + ahead of us or as rising + up ahead of us. But in this sentence, both interpretations come out to mean almost the same thing.

However, even though up is part of a phrasal verb or a phrasal preposition, its meaning as an individual word still influences the listener's imagination. If the listener hears rising up as the verb, the version with up suggests that the hillsides have a steeper slope than the version without up. If the listener hears up ahead of as the preposition, the version with up suggests that the hillsides are closer than the version without up.

The differences are very subtle, though, and probably not important. With some additional context, I think I could even hear the up ahead of interpretation as suggesting that the hillsides are far ahead.

Not really. Not when I put any thought into it, at least. They seem synonymous.

I suppose--and this is really an "I suppose"--"rise up" as used in that context makes me think a little more of the height of them. "Rise" is essentially indicating that the hills have a higher maximum altitude than where we are. That could mean even just by a few feet (even though I wouldn't read it that way). On the other hand, "rise up" almost makes them intimidating. It rings of "the hills are towering over me," which is a very different feeling.

Although that said, I'm not sure I'd even go that far in my subconscious if I were actually reading that in a real-world situation. Particularly in the context of "lush green hillsides," it's pretty clear that "intimidating" isn't the goal.

On top of that, clearly "rise" implies, if not even means, the same thing, but I think the word "rise" kind of falls to the background when I read it. It reads as filler text, and that's not a bad thing at all of course, but when you explicitly say "rise up," it really jolts me that "hey, this is definitely something I should be paying attention to."

So, yes, when I really think about it, I suppose they do have some discernable qualities. But in reality, I don't think I'd take notice. Especially if they weren't placed together for direct comparison.