Final answer:
Rough ER is characterized by the presence of surface ribosomes involved in protein synthesis, while Smooth ER lacks ribosomes and handles processes like lipid synthesis and drug detoxification.
Step-by-step explanation:
The key distinction between Rough Endoplasmic Reticulum (Rough ER) and Smooth Endoplasmic Reticulum (Smooth ER) is that Rough ER is studded with ribosomes on its surface, which are responsible for protein synthesis. These ribosomes give the Rough ER a 'rough' appearance and facilitate the production of proteins that are then distributed throughout the cell or secreted. In contrast, Smooth ER does not have these ribosomes and is involved in functions such as lipid synthesis, calcium ion storage, and drug detoxification. The absence of ribosomes gives the Smooth ER a 'smooth' appearance, distinguishing it visually and functionally from Rough ER.