Running uphill will definitely exhaust you faster if you try to keep a too fast pace. On the other hand, if the hill is not too steep, it doesn't have to be much harder than running on a flat surface.
Running downhill really depends on your technique and what conditions are you running in. It will be completely different if the road is wet or otherwise slippery, as you will have to put in a lot more energy to keep your balance. But if the road is dry and you have good shoes, it can be pretty easy with some practice.
I have this 1.5km long climb on my regular jogging track, which is quite steep. I live on top of the hill, so at first I have to run down, and at the end of the track run it back up.
If I'm running it in good weather conditions, I can run down pretty fast, feeling confident that I won't slip and basically don't get tired at all. But if it is a rainy day, I take a huge care with every step, making it almost as exhausting as running back up.
The difference with running up is that it is almost always the same, no matter the weather conditions.