The first point to note is the 'fan' branch configuration from downwards around the lower margin to more upwardly inclined in the canopy, which prevails regardless of the trunk structure. This is also a pattern which is very prevalent with conifers.
The second is the nature of the trunk, from dominant single trunk through to divided and where divided, the different levels of division.
In looking at trees these are the things to look for, to carefully observe.
In the book I created three sketches to illustrate the point. Here they are again.
I've recently been to the UK, in the middle of the northern hemisphere winter. The days may have been short and the weather cold and damp, but the trees were magnificent in their leafless state.
This first one is a great study of a deciduous tree's canopy. Its hard to see the rest of the tree but you get a sense of the fan branch configuration, with the lower branches closer to the horizontal plane. In the canopy the dominance of any one primary trunkline is diluted by the mass of fine branches with an upward inclination. As a model for bonsai this means that the canopy is shared and supported by many branches and because of their number none gains in disproportionate weight.