It seems that the main difference between a blood line clan and a regular clan is that bloodline clans seem to all have physical attributes and/or abilities every one in the clan shares. The only exeption to this would be Haku's clan. He doesn't seem to have any physical attributes that his clan would share (unless all the men look like girls ), and he doesn't seem to have any clan related abilities. I believed that the blood line ability of some one in a blood line clan doesn't need handseals to be activated, but maybe to enhance(Neji performing hand seals to use his x-ray vision). All of Haku's skills during that fight seem to be jutsu's(he used hand seals). The only ability that haku seems to have gotten from his clan is the one-hand seal ability he shows. Since it is clear because even kakashi, who has been through many missions and is quite good at gathering information, had never seen one-hand seals seems to suggest that it is not only Haku's blood line ability but also that he is probably the last of his clan. Regular clans seem to have a common jutsu and genetic characteristics. This leads me to believe that blood line clans were at some point in the past regular clans, and they have just evolved to the next level. I would assume that clans like the nara will eventually form blood line abilities in time. Perhaps in the Nara's case the ability to create and munipulate shadows without being near them(maybe a shadow tattoo on their bodies to link them with a pysical attribute), or the Chouji's clan being able to increase or decrease the size of different objects. I don't know how long it takes a regular clan to become a bloodline clan. I will assume that Kidomaru was from a blood line because of his unique non-jutsu abilities, but I am not sure arout Sakon and Ukon. It also seems that most blood line clans choose to align with a village, rather then being a part of the village. I notice this when the Hyuuga simply are not seen mingling with the public, they seem to stay in their own part of town with other Hyuuga's. The same goes for the Uchihi's. Any thoughts on my theories?