But these proteins synthesized by the free ribosomes end up staying within our cytosol. So that's the main difference between the ribosomes found inside the rough and the plasma reticulum and the free ribosomes, the ribosomes in the Er basically create proteins that either leave that cell or end up being in the cell membrane. However, the proteins created by the free ribosomes stay in the cytosol. Now, what exactly is the difference between cytosol and cytoplasm because the two are sometimes confusing or confused. Basically, the cytoplasm is the region between the cell membrane and the nucleus. And the cytoplasm includes all the organelles and all the structures found between these two sections.