My experiences are based on 6 years of living and driving in Boston compared to 3 years in Europe. In Boston they are aggressive but not cautious. The bulk of my time on Boston roads I find trying to "anticipate" what other drivers will do.

In Europe, I have more faith to the other drivers of the road, and I find more time making sure that my judgments are correct. Judgments such as how fast I am driving going into a sharp turn, or if I will have enough time to pass another car by going into the opposite lane with head on traffic.

Let me give you an example. I was driving in a Eastern European country. I had to pass in opposite lane. As I begin passing the truck, the driver knows that I am passing him (going into opposite lane, head on traffic) and he slows down. When he saw that it's a tight scissors pass he slowed down so I could pass adequately. When I tried this maneuver in Maine, the person I was passing was pissed off I was passing them (even though they were driving 40 mph on a 55 mph road) and when I began opposite lane passing (with proper signaling) they speed up so I could not pass them. With head on traffic this is dangerous. The other person was shocked I would do that and offended. However, everything I did was legal. The markings were stripped (which means I could pass) and he was driving below the speed limit. But he did not realize that he created a dangerous situation for me.

Sure they are subjective, but so are everyones.

To add to the subject:

1) In Europe, you have to know the proper road marking legislation. Speed limits are not always posted as they are in the US. For example, if you are driving on a rural road, there is know speed limit for such road (like 60 KM/H). Other roads have 80 KM/H. The big "Speed limit 60 km/h" sign is not going to be there. You have to judge and know what type of road you are on. Secondly, the markings of other signs as well are unknown to most Americans. These also vary from a country to a country. In the US, it's usually clearly spelled out SPEED LIMIT, STOP, etc. In Europe, it is not.

2) Enforcement - the bulk of road enforcement is based on a quota system. In 90% cases you find cops giving tickets on highways. In Europe, cops tend to be a lot more careful as to other rules. For example, turning without signaling, or pulling out of the gas station in the opposite lane. In the US, everyone does it, in Europe if a cop sees you doing it you are pulled over. Passing is always done on the left, never on left and right (unlike the US). And you cannot go to the most left hand lane (continental Europe, not the UK) and drive 70mph on cruise control. On highways, there are lanes for cruising and then lanes for passing. In the US, everyone does what they want. In Europe, a cop would pull you over if he sees you in the left hand lane just cruising along.

There are differences between US and Europe driving. This does not mean that a US driver cannot drive in Europe and vice-versa. But there are little adjustments. I don't want to discourage American drivers from driving in Europe, but just be more attentive and cautious.

All of this is purely subjective.