The scientific classification of Allamanda and Crown-of-Thorns includes the entire classification chart that includes kingdom, family, clade, tribe etc. A kingdom is the second highest taxonomic rank. A taxonomic rank is the level that a living organisms are placed in hierarchical level of arrangement of life forms. All the living organisms are divided into kingdoms. Plant kingdom is a main classification of living organisms that include all plants. There are six kingdoms which are: Plantae, Animalia, Fungi, Protista, Aschaea/Archaeabacteria and Bacteria Eubacteria. Allamanda and Crown-of-Thorns kingdom and all other plants kingdom is Plantaea.
Plant family is the group of plants which have something in common. Allamanda and Crown-of-Thorns family is a major factor of Allamanda and Crown-of-Thorns Scientific Classification. Plant family helps you narrow the search of your plants. It also gives you idea about, how the plant looks, how the seed will be like etc. These two plant families can be different or same. Allamanda belongs to the family Apocynaceae and Crown-of-Thorns belongs to the family Euphorbiaceae.
While comparing scientific classification, Allamanda and Crown-of-Thorns genus and other classification are also important. Also, when you compare Allamanda and Crown-of-Thorns, other factors should also be taken into considerations like order, subfamilies, tribe, clade etc. First plant's genus is Allamanda and other plant's genus is Euphorbia. Allamanda tribe is Apocyneae and Crown-of-Thorns tribe is Euphorbieae. Allamanda clade is Angiosperms, Asterids and Eudicots and order is Gentianales whereas Crown-of-Thorns clade is Angiosperms, Eudicots and Rosids and order is Euphorbiales. Every plant have subfamilies. Allamanda subfamilies are, Rauvolfioideae and Crown-of-Thorns subfamilies are Euphorbioideae. In this way you can compare scientific classification of Allamanda and Crown-of-Thorns and other products also.