If you look at species of bees and ants, you can clearly see there are drastically different specialized ants, like queen ants and workers. They're both part of the same species, yet are still obviously different. What is the proper name for that phenomena?
In eusocial insects, especially ants and bees, these groups are called "castes" (see e.g. Hölldobler & Wilson, 1990. This is the same term that is used for social stratifications in some human societies e.g. in India.
One definition of caste is:
...the physical or the behavioural/physiological phenotype of a eusocial individual, or both.
(from Hölldobler & Wilson, see also antwiki.org)
Some division of labour as well as collective rearing of young can occur in prosocial animals as well, but there the term caste is not used.