On Terraforming: A lot depends on what you mean by terraforming.
I take it to mean doing the minimal engineering necessary for human beings to flourish unprotected on the surface of a planet. This may mean adding water and air, or changing the composition of the air. Depending on the orbit of the planet and the characteristics of its star, there can be some bigger issues too. But let's assume your engineers picked a planet in the Goldilocks zone, one that has a reasonably low eccentricity.
If the planet had no air, your engineers found a way to add both air and water. The most economical way to do that is to bombard the planet for years with icy chunks gleaned from the outer system. (I am presuming a planetary system not too different than our own.) Glossing over the fact that the new atmosphere may not be breathable, we can say a couple of things about the planet that will be different than Earth:
1) It's smaller than Earth (in the Goldilocks zone and little or no air to start with).
2) Since it's smaller and had no large amount of water, it probably does not have a well-developed tectonic system.
3) With no air and sluggish or nonexistent tectonics, much of the surface will be primordial - read lots of craters and little erosion. This primordial surface will show in the landscape. Someone has done a map of a 'wet' Mars, which shows what it might be like if we could flood the surface of Mars. Lots of round seas in the big craters.
If the planet is Earth-sized to begin with, and has no or little water, it will likely have a heavy carbon dioxide atmosphere. Most of Earth's carbon is locked up in rocks through the action of water - it probably started with as much carbon dioxide as we see on Venus, but cooler temperatures allowed liquid water which, over geologic time, dissolved the carbon dioxide and locked it up in sediments. I don't know how your engineers get rid of the excess carbon dioxide, but I would assume that the heavy atmosphere present until they did would result in a more eroded landscape with lower, more rounded landforms. With no historical water to erode channels, water will collect in every hollow. Your landscape will have lots of lakes.
In either of these cases, the landforms will be inconsistent with the terraformed climate. An astute observer might discover these inconsistencies and conclude something changed in the recent past.
If your world has water and air (you can't have water without air), then it will look more or less like Earth. An Earth-sized planet will sustain tectonic activity for billions of years, so you have all the forces present that shape the Earth. If your planet is much older than Earth, tectonics may have slowed or even stopped. In this case, mountains will be more eroded and no new ones will form. But there will be no obvious sign that the past was very different than the present.
If your planet is very young, cratering will be more in evidence, and possibly volcanism will be more common. Your engineers may need to do some miracle to keep the debris floating around the system from landing on the colonists' heads. If they don't, an astute observer may notice (just before he's flattened) that the climate is inconsistent with the obvious youth of the system.
You can get into this in far more depth, but it gives you some ideas where to start.