Simple tissues in plants are made up of only one type of cell, which have a similar structure and perform a specialized function. Examples include parenchyma, collenchyma, and sclerenchyma. These tissues are generally involved in functions like photosynthesis, storage, and support. In contrast, complex tissues consist of more than one type of cell working together to perform a function. Examples of complex tissues are xylem and phloem, which are involved in the transportation of water, minerals, and food throughout the plant. Complex tissues have a more organized structure and contain specialized cells for their respective functions. In summary, the key difference is that simple tissues are homogeneous, made of similar cells with common functions, while complex tissues are heterogeneous, composed of diverse cell types functioning collectively in transport and other roles.