Homologous chromosomes are a pair of matching chromosomes —one from each parent—that carry the same genes in the same order, but they can have different versions of those genes. Sister chromatids are the two identical copies of a single chromosome made after DNA replication and joined at the centromere.

Simple difference

  • Homologous chromosomes: similar, but not identical.
  • Sister chromatids: identical copies.

Where they come from

  • Homologous chromosomes come from mom and dad.
  • Sister chromatids come from copying one chromosome before cell division.

How they behave

  • Homologous chromosomes pair up during meiosis.
  • Sister chromatids separate during mitosis and also during the second division of meiosis.

Easy way to remember

Think of homologous chromosomes as two editions of the same book, and sister chromatids as two photocopies of the same page. The book editions are similar but may have small differences; the photocopies are meant to match exactly.

Feature Homologous chromosomes Sister chromatids
Source One from each parent Copied from one chromosome
Genetic content Same genes, possibly different alleles Same genes and same alleles
Connection Not joined by a centromere Joined at a centromere
Main division role Pair in meiosis Separate in mitosis and meiosis II
TL;DR: homologous chromosomes are a matched pair; sister chromatids are identical copies of one chromosome.