So a tissue is a collection of cells that are similar or have a similar function, not to be confused with the tissue you blow you nose with.

Cells are the smallest unit of life and when a bunch of cells are doing the same thing, they group together into a tissue. An example would be that in the heart, which is made of tissues that make the walls of the heart and other tissues that pump the blood. An organ is a collection of multiple tissues and it has a specific function in the body. So the heart is responsible for pumping blood through the body and the heart tissues are the various pieces of the heart. These pieces of the heart are important, but can’t pump blood on their own; they need the help of other tissues to form an organ.