We study bridging transitions between spherically and cylindrically shaped particles (colloids) of radius
R separated by a distance H that are dissolved in a bulk fluid (solvent). Using macroscopics, microscopic
density-functional theory, and finite-size scaling theory, we study the location and order of the bridging transition
and also the stability of the liquid bridges, which determines spinodal lines. The location of the bridging transitions
is similar for cylinders and spheres, so that at bulk coexistence, for example, the distance Hb at which a transition
between bridged and unbridged configurations occurs is proportional to the colloid radius R. However, all other
aspects, particularly the stability of liquid bridges, are very different in the two systems. Thus, for cylinders the
bridging transition is typically strongly first-order, while for spheres it may be first-order, critical, or rounded as
determined by a critical radius Rc. The influence of thick wetting films and fluctuation effects beyond mean field
are also discussed in depth.