Do comet orbits lie in the same plane as the other planets?
Those two comets happen to have large orbital inclinations to the Ecliptic: 117$^\circ$ for
C/1858 L1 (Donati)
and 162$^\circ$ for
1P/Halley.
Long-period comet orbits are oriented essentially at random, suggesting that they originate in the
Oort cloud,
a sphere several thousand AU from the Sun.
Many short-period
comet orbits are inclined only a few degrees to the Ecliptic,
suggesting origins in the
scattered disc,
a torus several tens to a few hundred AU from the Sun.