Zombie bites and Zombie-fication ... i.e. re-animation ?

If it was just a normal bite the people would die from different things,
infections, septicemia, gangrene, etc. and if people who cleaned their
wounds might not die at all.

So, there must be something unique in the bite of a Zombie, some new
kind of infection that is connected to the certain death of the infected.

The zombification of a person is another issue, because one does not
need to be bit to end up re-animating as a zombie.

The problem is that in the world of "The Walking Dead", the infection and
the zombification of all people who have died happened at the same time,
presumably world-wide.

So the question is, what, if anything, connects the zombie infection and
subsequent death with the zombification re-animation as a zombie?

If there any difference between a zombie that dies without being bit, and
the zombies that die after being bit?

A corollary to this question is ... what about people who are overwhelmed
by zombie and have been half or fully eaten ... they must go through the
same process, but when they re-animate they are all messed up? What
about those zombies.

Occam's Razor tells us to first go with the simplest explanation that
fits the facts, so we know two things:

1) people who are bit die and turn into zombies.
2) people who die in any way turn into zombies.

So, there are two things at work here. An infection that ultimately
kills the victim when they are bitten, and the process of becoming
a zombie when one dies ... which can be almost instantaneous,
or can take an entire night or at least several hours?

My question would be, how long after you are a zombie would
your bite be fatal? Maybe when you turn into a zombie, and
already existing minor infections moves throughout your body
and ends up re-animating you ... and that process can be fast
or slow depending on other factors.