Generally, inquiries in philosophy of physics concern foundational issues in the sciences. A "foundational issue" is a problem in the "foundations" of a particular science. For instance, the measurement problem is a foundational issue in quantum mechanics; the compatibility of general relativity and quantum field theory is a foundational issue for those two sciences; the justification of the second law of thermodynamics is a foundational issue in statistical mechanics; the proper understanding of the concept of a species is a foundational issue in biology; the justification of the principle of natural selection is a foundational issue in evolutionary biology; and so on. Philosophy of physics questions tend to be specific to a particular science; and they tend to be questions that practitioners of those science worry about in their philosophical moments but don't need to address in order to practice the science.
In contrast, inquiries in philosophy of science tend to address broader concerns that arise from thinking about science. Questions in the philosophy of science include: what does it take for something to be a scientific explanation; what is a law of nature; what is the correct measure of the degree to which a piece of evidence confirms a theory; what is the nature of a scientific theory; how does science differ from non-science; what is the best way to characterize relations between theories; and so on. Answering these questions often involves appealing to details about individual sciences and scientific practice; but generally the relevant details can be found in more than one science.
I'm sure there's lots missing from this sketch; but I think it highlights some essential differences.