actually a "hoodrat" refers to a female in a low-social-status or low-income-status environment ( a ghetto, a trailer-park, etc) who displays no dignity or self-respect and who lacks intelligence in basic decision-making. she is usually promiscuous, loud, brazen, addicted to drugs or alcohol, short-tempered and is usually not very bright.
a thug also has a wide range of personifications: a "thug" refers to a male (usually) who uses street-smarts, muscle, and/or illegal activity to acquire social status and money. they could be mobsters, drug-dealers, street hustlers, thieves, and even body-guards or muscle-men who complete "dirty work" in exchange for money or police protection.
neither of these terms refer to solely a black person, or solely a white person, for that matter. their universal: the same way that "idiot" and "slacker" and "looser" have no racial boundaries...they could apply to anyone who fits the definition.
-hbb