The scientific classification of Hydrangea and Oleander 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. Hydrangea and Oleander kingdom and all other plants kingdom is Plantaea.
Plant family is the group of plants which have something in common. Hydrangea and Oleander family is a major factor of Hydrangea and Oleander 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. Hydrangea belongs to the family Hydrangeaceae and Oleander belongs to the family Apocynaceae.
While comparing scientific classification, Hydrangea and Oleander genus and other classification are also important. Also, when you compare Hydrangea and Oleander, other factors should also be taken into considerations like order, subfamilies, tribe, clade etc. First plant's genus is Hydrangea and other plant's genus is Nerium. Hydrangea tribe is Not Available and Oleander tribe is Wrightieae. Hydrangea clade is Not Available and order is Cornales whereas Oleander clade is Angiosperms, Asterids and Eudicots and order is Gentianales. Every plant have subfamilies. Hydrangea subfamilies are, Not Available and Oleander subfamilies are Apocynoideae and Hippocastanoideae. In this way you can compare scientific classification of Hydrangea and Oleander and other products also.