T-cells and antibodies are both essential components of the immune system. Although they are both involved in protecting the body against pathogens, they play different roles in the immune system. 

T-Cells

• T-cells are a type of white blood cell that develop in the thymus and play a critical role in the immune system. They are also called T lymphocytes. 

• T-cells originate from hematopoietic stem cells in the bone marrow, then travel to the thymus gland where they mature and differentiate into one of the types of T-cells in the body. 
• The structure of T-cells varies depending on specific types but all types feature T-cell receptors with complex structures on their membrane surface. These receptors are made up of several polypeptide chains. 
• There are two types of T-cells – Cytotoxic T-cells or killer cells, which are directly involved in killing harmful cells and Helper T-cells, which are indirectly involved by helping to coordinate immune responses.

Antibodies

• Antibodies are specific types of proteins that bind to pathogens and help neutralize them. They are also known as immunoglobulins.
• These protein molecules are composed of about 4 polypeptide chains and various chains with specific regions tailored for binding to antigenic substances. 
• Antibodies originate from stem cells in the bone marrow. They are synthesized and released by the B cells in the body in response to signals from T-cells.  
• There are 5 types of antibodies – IgA, IgE, IgM, IgG, and IgD. Each type is distinct in terms of function, structure and location. 
• Antibodies inhibit the action of pathogens by binding to antigens on the surface of pathogens, which prevents the pathogen from synthesizing essential proteins.