Models are very helpful, but they also have limitations.
Details—Models cannot include all the details of the objects that they represent. For example, maps cannot include all the details of the features of the earth such as mountains, valleys, etc.
Approximations—Most models include some approximations as a convenient way to describe something that happens in nature. These approximations are not exact, so predictions based on them tend to be a little bit different from what you actually observe. Models do not behave exactly like the things they represent.
Accuracy—In order to make models simplistic enough to communicate ideas some accuracy is lost. For example, ball and stick models of atoms do not show all the details that scientists know about the structure of the atom.
Real dinosaurs cannot be studied because they died out long ago.