How are eukaryotic cells differentiated from prokaryotic cells?

Eukaryotic cells are primarily differentiated from prokaryotic cells by the presence of a nucleus. In eukaryotic cells, the genetic material (DNA) is enclosed within a membrane-bound nucleus, which is a key feature that distinguishes them from prokaryotic cells, where the DNA is not contained within a nucleus and is typically found in a region called the nucleoid. This structural distinction is fundamental to the classification of cells into eukaryotes and prokaryotes, significantly affecting how these cells carry out processes such as replication, transcription, and translation.

While size may vary between the two cell types, this is not a definitive characteristic as there can be overlaps. Age is unrelated to the classification but pertains to the life cycle of the organisms themselves. Dependence on sunlight is specific to certain organisms (like plants) and does not serve as a general differentiator between the two types of cells. Thus, the defining feature is indeed the presence of a nucleus in eukaryotic cells.