Long range scopes need a couple capabilities. I'll lay 'em out for you.
1.Good turrets / knobs. As a rule, we dial in our elevation changes. This means we dial for the distance. You want rugged, clearly marked turrets with positive clicks. The knobs need to be big enough and textured enough to turn in hunting conditions. They need to be stiff so they don't turn accidentally. Small covered turrets tend to be too soft, difficult to manipulate, and you lose the damn caps.
2. Good tracking. This means if you dial the scope for a 1000 yard shot, then back to zero, the crosshairs move where they are supposed to, every time. This is the heart of a long range scope
3. Parallax adjustment. Basically, crosshairs are focused for a particular range. Most typical hunting scopes are set around 150 - 200 yards. To illustrate the idea look through a scope at something close to you, say ten yards. Now move your head just a bit. It will appear the crosshairs move all over the place. Where would the bullet hit? Parallax is dealt with in two ways. One is an adjustable objective, the other is a side focus knob. Simply turn the knob to the appropriate shot distance and the bullet will hit where intended.
4. Enough elevation adjustment. The scope needs to have enough travel to hit whatever range you want to shoot at. Most long range scopes have enough elevation adjustment to shoot magnum calibers to a mile or so.
5. A good adjustment system. We compensate for the range using several systems. Minute of angle, Mil, and bullet drop compensation systems are the most common. You can check out the particulars of each system. I use MOA, or minute of angle almost exclusively because it is very flexible and intuitive. It's a good idea to shop for a scope with matching turrets and reticle. For example, minute of angle turrets and reticle, or mil turrets and reticle.
From this point, everything else is gravy. Some scopes offer illuminated reticles, big tubes, big objectives, threaded bells for scope covers... You can choose first or second focal plane. This means either the reticle for a particular system will visually remain the same size at all magnification and work at only one power setting, or the reticle will visually change size according to magnification and work on all power settings.
I know it's a bit to absorb. Don't hesitate to keep asking questions. Cheers.