whore can denote a number of things, from 'loose morality', to being available for multipe sexual encounters, some sense of need or longing, to a number of mental/emotional issues that one tries to resolve with sex (ie. low self esteem, finding validation in physical contact/ the mis-association of the whole sex=love thing) etc.
a prostitute.. does it for the money (as well perhaps as some of the above mentioned causes)
trust me on this one, sorry if I can't explain it well.. I'll post a thread as to why here in a bit.. and also having done some whoring myself.. (a little trickier when you are male
)