Here’s a very simplified way of thinking about the main differences between civil and common law. It really comes down to where you find the law.
Under civil law, politicians can make law via statutes. Judges find the law in those statutes. Decisions by other judges, and common practices by people, may affect how judges interpret the law they find in the statutes, but ultimately the law is only found in those statutes.
Under common law, judges can find law in statutes, but they can also find law sitting under trees, in in the back of old cupboards, or in their washtubs.
Under common law, a judge might find that there is a law simply by virtue of people always having done something a certain way. (A really good example is to compare the American constitution to the English constitution – the American one is pretty much written down; whereas only parts of the English constitution are written down in a great many different documents that have traditionally come to be considered of constitutional importance, or are not written down anywhere but are simply understood to be of constitutional importance by tradition/convention.)
Also under the common law, when interpreting laws, decisions by judges higher up the ladder are usually supposed to be binding (have the force of law) on lower courts.
As far as judge made law goes, under the common law system, judges that don’t want to be bound by a higher judge’s decision simply distinguish that higher decision by pointing out how the circumstances are sufficiently different to the degree that the higher judge’s decision should not be followed; and in the civil law system, although a higher judge’s decision does not usually have to be strictly followed, a lower judge will seriously consider a higher judge’s decision, particularly with a view to how an appeal court might decide the matter.
Despite the fundamental difference between the two systems of law in theory, there is very little difference between them in in practice. Governments create more and more laws, and often these laws start off by making a clean slate of old common laws. This makes the common law system more and more like the civil system.
Thus there is not a whole heck of a lot of difference between the systems down where the rubber meets the road.