So, I thought I'd do a vampire mythology comparison of Buffy and True Blood since both mythologies are so different.
BTVS: Vampires have no reflection.
True Blood: Vampires have a reflection. Bill would prefer Sookie not spread this around since it's a myth the vampires made up.
BTVS: Buffy gets an 'aspect of the demon' in Season 3's 'Earshot' and can hear everyone's thoughts. She attempts to read Angel's mind when he is being extra-taciturn, but he's the only one she can't hear. Angel explains that the thoughts are there, but cannot be reflected, like the mirror.
True Blood: Sookie has telepathic powers throughout the show and has trouble shutting out everyone's thoughts. But, when she's with Bill, she can't hear his thoughts, and thus, finds his presence most relaxing.
BTVS: Buffy has only really used garlic twice in the show, but we never saw a vampire recoiling from it. She hung it from her bed to keep Angelus away during season 2 in 'Passion' and to keep Spike away during Season 6.
True Blood: Bill finds garlic "unpleasant."
4. Crosses/Holy Water
BTVS: Vampires feel the burn when sprayed with Holy Water or when touching a cross. They hiss, sizzle, and can die if the exposure is extended. For example, Buffy killed a vampire by tricking him into drinking Holy Water. When presented with a cross, vampires hiss and recoil. They can barely look at them.
True Blood: Vampires don't mind being in the presence of crosses. The use of Holy Water never came up in the show, if I remember correctly. And I don't think any of the vampires touched a cross, but I'm sure the reaction for both crosses and Holy Water would be similar to Buffy; lots of sizzling and hissing.
BTVS: Silver has no effect on vampires.
True Blood: Silver burns into vampires' skin, leaving horrible marks. It weakens them and can incapacitate them.
BTVS: If a vampire is caught in direct sunlight, he or she will burst into flames and die. However, vampires can deal with indirect sunlight, such as having a cloth over them or standing in the shadow if the sun is low enough in the sky.
True Blood: They will not die instantly, but vampires will be severely weakened by the sun. Their vision will become blurry and their skin will gradually burn off. The only way to recover is to be buried underground (or put into a dark room, I assume) and then to feed immediately when night falls.
7. Inviting into Homes
BTVS: Vampires cannot come into a home without express invitation ("I invite you in." "Come in."); this includes hotel rooms and dorm rooms, as well. Once a vampire has been invited once, he or she can always re-enter at their will. The only way to reverse this is to perform a spell.
True Blood: Vampires cannot come into a home without express invitation. The invitation has to be very specific in inviting them, as well. They can be sent away from the home if the person who invited them retracts their invitation.
8. Vampire Blood
BTVS: Vampire blood has no special quality, except to make new vampires.
True Blood: Vampire blood is sold as a very expensive drug. Its effects are similar to those of mushrooms, ecstasy, and other hallucinogens. Hallucinations and enhanced sexual pleasure are its main effects, as long as only one or two drops are taken.
9. Human Visage to Vampire Visage
BTVS: When a vampire transforms from his human face to his vampire face, it is not a pretty site. His or her fangs grow, the brow pushes inward and becomes wrinkly, and the eyes turn yellow.
True Blood: When vampires change from their human features to vampire features, they sprout fangs on either side of their front teeth and their eyes glow. The rest of their features remain human.
10. Speed, Strength, Agility
BTVS: Vampires are great fights, inheriting kung-fu skills from the moment they crawl out of the ground. They cannot fly, but they can jump great hights.
True Blood: Vampires have super speed. They move at the speed of light and seem to be able to hover above the ground in a way during this super speed movement. They also have super strength and are able to fabricate a tornado destroying someone's home.
BTVS: A vampire must drain the blood of a human to the point before death. Then, the vampire must let the human drink his or her own blood. A burying ritual is not necessary, but usually done regardless.
True Blood: Similar to BTVS, except that the burying ritual seems to be necessary to complete the transformation. The sire must also sleep with the new vampire underground during the transformation.
BTVS: A simple wooden stake in the heart and a vampire, including its clothes, will turn to dust.
True Blood: A stake to the heart and the vampire will spew mass amounts of blood from its mouth and explode into a bloody mess of clothes and other stringy material. It's hard to say what exactly is left behind, but definitely a lot of blood.
I'm glad vampires on Buffy didn't die that way or Buffy would have ruined some fabulous outfits. ;)
13. Vampire Laws
BTVS: Vampires who are bound to a Master must obey rules that the Master vampire decides. But, most vampires do their own thing.
True Blood: All vampires live by a specific code, whose rules haven't exactly been disclosed. From the show, it is clear that certain vampires, especially older vampires, have authority over others. And killing another vampire results in a trial of vampire peers, punishable any numbers of ways.
That's all I can think of! If missed any vampire traits or forgot a specific detail, feel free to let me know!