Nerve cells communicate by sending an electrical signal through an axon, from this molecules get released into the synapse this then binds itself onto receptor sites. With ion-linked channel receptors, the ligands get binded to a protein. The ion channels are then opened and the proccess gets repeated. Does that help?
The most observable difference is the way in which cytokinesis occurs. In plants a new cell wall is fashioned between the new daughter cells, while in animal cells the cell membrane constricts to pinch the parent cell into daughter cells.
The bald eagle and the black bear are tetrapods, which means that they both have four limbs along with the digits. This shows that they both are the descendants of the four-limbed ancestors. However, the limbs of the bear and the bald eagle have different functions. The forelimbs of both these organisms serves different purpose. Hence, their limbs are homologous organs. The homologous organs are those which have the same ancestry but the functions are different.
