  Statistics of the angle \Phi between orbital angular momenta in hierarchical
triple systems with known inner visual or astrometric orbits are studied.
Correlation between apparent revolution directions proves partial orbit
alignment known from earlier works. The alignment is strong in triples with
outer projected separation less than ~50 AU, where the average \Phi is about 20
degrees. In contrast, outer orbits wider than 1000 AU are not aligned with the
inner orbits. It is established that the orbit alignment decreases with
increasing mass of the primary component. Average eccentricity of inner orbits
in well-aligned triples is smaller than in randomly aligned ones. These
findings highlight the role of dissipative interactions with gas in defining
the orbital architecture of low-mass triple systems. On the other hand, chaotic
dynamics apparently played a role in shaping more massive hierarchies. Analysis
of projected configurations and triples with known inner and outer orbits
indicates that the distribution of \Phi is likely bimodal, where 80% of triples
have \Phi<70 degrees and the remaining ones are randomly aligned.
