Jen (wren): human heartedness; goodness; benevolence, man-to-man-ness; what makes man instinctively human (that which gives human beings their humanity).
The first principle of Confucianism is to act according to jen: it is the ultimate guide to human action.
Jen is a sense for the dignity of human life--a feeling of humanity towards others and self-esteem for yourself.
There is the belief that jen can be obtained; indeed, there is the belief in the natural perfectibility of man. Hence, he rejects the way of human action where one satisfies likes and avoids dislikes.
Such feeling applies to all men--not just one nation or race. It is the foundation of all human relationships.
Li (lee): principle of gain, benefit, order, propriety; concrete guide to human action.
Confucius recognized that you need a well ordered society for wren to be expressed.
Two basic meanings to li: (1) concrete guide to human relationships or rules of proper action that genuinely embody jen and (2) general principle of social order or the general ordering of life.