ofcorse they are. but there is a distinct diffrent between fallen angels and deamons.
there are 1/3 of heven that fell with satan.
the next some people will dispute as rumor. adams first wife lillith, born of dust like adam. ate the forbidden fruit, risisted adam and spoke the ultra-seceret name of god. refusing to lay beneth adam.
lilith was taken away and eve was created. but it is not the last time we hear of lilith, she is is said by stories to be the mother of deamons, impregnated by sexual relations that produse no fruit. (masterbation, homosexual acts, birthcontroll, ect). these acts cause lilith to produse deamons.
man and woman = human child
lillith and man = deamon
it is also rumored that caine met lillith in the land of nod, and so is born the human like deamons such as vampires.
but this is mith with little fact other then it stating lillith in isaica, and the common sence that caine reproduced with some one.