A dog hybrid is the result of cross breeding two different and recognized dog breeds. “Recognized” implies a pure breed although this can be a subjective standard since the list of “pure breeds” keeps changing and growing.
A mongrel is a dog with unknown ancestry and may be the result of the cross breeding of two or more breeds or hybrids.
Logically, a mongrel may actually be a hybrid. But because the breed of one or both parents is unknown, it is considered a mongrel.
That’s our dog, Twix, in the photo. Sam’s dog, actually. He’s a pomspitz, a cross breed of a pomeranian and a Japanese Spitz. It appears that the pomspitz is unique to the Philippines. I have searched Google far and wide and all references to “pomspitz” point to a Philippine source.