Here's why:

* Membrane-bound organelles: Eukaryotic cells have a variety of membrane-bound organelles, such as the nucleus, endoplasmic reticulum, Golgi apparatus, mitochondria, lysosomes, and chloroplasts (in plants). These organelles compartmentalize cellular functions, allowing for greater efficiency and specialization. Prokaryotic cells lack these organelles.

* Nucleus: Eukaryotic cells have a true nucleus, which contains the cell's DNA. This allows for the regulation and protection of genetic material. Prokaryotic cells have a nucleoid region, where DNA is concentrated but not enclosed by a membrane.

* DNA structure: Eukaryotic DNA is linear and associated with histone proteins, forming chromosomes. Prokaryotic DNA is circular and typically not associated with histones.

* Size and shape: Eukaryotic cells are generally larger and more diverse in shape than prokaryotic cells.

* Cytoskeleton: Eukaryotic cells have a complex cytoskeleton, composed of microtubules, microfilaments, and intermediate filaments. This provides structural support, facilitates movement, and helps with cell division. Prokaryotic cells have a simpler cytoskeleton.

* Cellular processes: Eukaryotic cells perform a wider range of complex cellular processes, such as mitosis, meiosis, and endocytosis.

In summary, eukaryotic cells have a more intricate and specialized internal structure, allowing for greater complexity and a wider range of functions. Prokaryotic cells are simpler, but they are incredibly efficient and adaptable organisms.