[eru]

There are two main sets of differences:

The conceptual differences, and the differences in content.

You are right that the conceptual differences are murkier in practice than in theory:

Even in civil law countries, judges tend to defer to precedent, even though they aren't strictly bound by it. And in common law countries, if you are a judge and you don't like a precedent (even a precedent set by a higher court), you can 'just' find enough differences between the case in front of you and the precedents you don't like, and argue away the differences with the precedents you do like.

Content-wise, there's a big difference in how eg German law sees contracts and how English law sees them. But you could (more or less) embed the English definition of contract in a civil law system, just as much as you could embed the German definition in a common law system.

In practice the main difference between English vs German contracts is in the legal boilerplate and fine print. You can think of the boilerplace text like a 'polyfill' or compatibility layer that gets you closer to what you actually want to implement in the main text of your contract.