There are a lot of answers to that question, because there are a lot of different branches of philosophy, and because it evolved over time.

I'd say philosophy is mostly the fact of thinking seriously about any subject. It can be meaning of life, morals, politics, technical objects, science, arts, perception, happiness, etc. Sometimes, when the study of one category of subject starts to be very complex, very distinct, it becomes a field of science in itself : maths, physics, biology can be seen this way, but economy, sociology could be too.

To me the difference experimentation/theoretical is a relatively correct observation, but it is a consequence of something slightly different : sciences are heavily structured, defined systems of thought. They depend on a set of concepts and rules that are accepted and that scientists try to refine. Philosophies are less strictly defined, challenging any commonly admitted concept is typical. So science already has a whole system that facilitates experimentation, while philosophy is questioning its own system and therefore is a bit more theoretical.

Another approach is to see science as "Okay, we have this thing. How does it work ?". Philosophy would be "But what is this thing ? Do we really have it ? Why is it there in the first place ? How can we be sure that we're studying it properly and not missing anything ?".