Small cells (1/100th the size of a body cell). They make you feel ill by damaging your cells and producing toxins.
Not Cells (1/100th the size of a bacterium). Replicate themselves by invading your cells and using that cells machinery to copy themself. Cell damage is what makes you feel ill.
Every invading cell has antigens on its surface. When your white blood cells come across foreign antigens, they produce antibodies. They lock onto the invading cell, they are specifically made to lock onto that type of cell and won't lock onto any other cells.
Some Relieve Symptoms ie pain killers (aspirin). They don't tackle the cause of the disease, they just relieve the symptoms.
Antibiotics Kill/prevent growth of the bacteria…