First of all there is no need to use foul language. Moderate your language, especially on social networks and public platforms.
Secondly, only supernatural beings are able to remove the heart from a vampire's chest in The Vampire Diaries, due to their enhanced streght or magical powers. In True Blood they are severely damaged by silver for its magical properties and only wood can destroy them, whether in the form of a stake or bullet, and only if it pierces the heart.
In both shows, beheading as a vampire execution is possible only to supernatural creatures because the vampire body is very strong and durable, ergo it requires special weapons and supernatural forces to be damaged.
In AHS, however, a normal bullet kills vampires like humans. If they are slaughtered by a common sharp knife or razor, they die. In other show vampires heal almost instantly, they don't have time to lose large amounts of blood. If they are hit by a bus, they die in AHS. Quoting Elizabeth "you are immortal only if you are smart", namely avoid to get involved in deadly situations.
Valentino and Natasha were practically mummified, I wouldn't say then, that they are immune from decay, which is one of the primary requirements to be considered immortal in the strictest sense of the term. They constantly need to feed. A true immortal, like a god, doesn't need to feed at all.