Among a number of generic tools that have been developed in the last decade to measure, explore, analyze, model and visualize plant architecture in 3-dimensions, this paper focuses on methods dedicated to the comparison between plant architectures. After a first step that has been reached with the comparison of branching sequences along axes, Ferraro and Godin have extended comparison methods to the whole branching systems. Their method was applied to the comparison of plants formalized as tree-graphs. In the last two years, new algorithms were explored and implemented in order to compare plant architectures with different relationships between components of the plant structure taken into account in the corresponding formal representations. The present paper provides a brief review of the comparison techniques now available to compare plant architectures depending on their formal representation. Their relative advantages / disadvantages are presented through an example of application on the comparison of two-year-old apple F1 hybrids.