  In the jet bundle description of Field Theories (multisymplectic models, in
particular), there are several choices for the multimomentum bundle where the
covariant Hamiltonian formalism takes place. As a consequence, several
proposals for this formalism can be stated, and, on each one of them, the
differentiable structures needed for setting the formalism are obtained in
different ways. In this work we make an accurate study of some of these
Hamiltonian formalisms, showing their equivalence.
  In particular, the geometrical structures (canonical or not) needed for the
Hamiltonian formalism, are introduced and compared, and the derivation of
Hamiltonian field equations from the corresponding variational principle is
shown in detail. Furthermore, the Hamiltonian formalism of systems described by
Lagrangians is performed, both for the hyper-regular and almost-regular cases.
  Finally, the role of connections in the construction of Hamiltonian Field
theories is clarified.
