When referring to a group of things or people that are very similar or closely related, the phrase "peas in a pod" is often used. However, there are several other synonyms that can be used to describe this type of group. Words such as "identical", "alike", "similar", and "indistinguishable" can all be used to convey the meaning of similarity. Another popular expression to describe a group of closely related things is "birds of a feather". This phrase also communicates the idea that individuals or objects in a group share similarities or have common traits.