In this paper we investigate "inertial forces" and "fictitious forces" and the relationship between them as understood from the literature of physics where the majority seem to consider them as two labels for the same thing while some seem to suggest they are not identical. Our view and preference is to distinguish between them where fictitious forces should be considered a subset of inertial forces. We also investigate the issue of the reality of fictitious forces and whether they have authentic existence in the physical world or they are a kind of "delusion". Our view is that what is called "fictitious forces" can be either. In this regard, we identify and propose several physical characterizations and distinctions between the two types (i.e. the "apparently fictitious forces" which are physically real and the "really fictitious forces" which are illusory because they are purely frame-dependent as viewed by a non-inertial observer). This is consistent with our preference that fictitious forces should be considered a subset of inertial forces, i.e. "inertial forces" which are real should not be classified as "fictitious" in the real sense while "inertial forces" which are not real should be classified as "fictitious" in the real sense.