The scientific classification of Old Man Cactus and Eggplant 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. Old Man Cactus and Eggplant kingdom and all other plants kingdom is Plantaea.
Plant family is the group of plants which have something in common. Old Man Cactus and Eggplant family is a major factor of Old Man Cactus and Eggplant 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. Old Man Cactus belongs to the family Cactaceae and Eggplant belongs to the family Solanaceae.
While comparing scientific classification, Old Man Cactus and Eggplant genus and other classification are also important. Also, when you compare Old Man Cactus and Eggplant, other factors should also be taken into considerations like order, subfamilies, tribe, clade etc. First plant's genus is Cephalocereus and other plant's genus is Solanum L. Old Man Cactus tribe is Pachycereeae and Eggplant tribe is Solaneae. Old Man Cactus clade is Angiosperms, Core eudicots and Eudicots and order is Caryophyllales whereas Eggplant clade is Angiosperms and Asterids and order is Solanales. Every plant have subfamilies. Old Man Cactus subfamilies are, Cactoideae and Eggplant subfamilies are Solanoideae. In this way you can compare scientific classification of Old Man Cactus and Eggplant and other products also.