My textbook doesn't do a very good job of pointing out what the differences between the two are. It basically mentions axons only in the same breath as the synapse (that synapses are the endings/tips of axons).
This reference is a bit basic, but lists the functions and differences between axons and dendrites. Specifically, dendrites receive signals from other neurons, to the cell body; whereas, axons take signals away from the cell body (essentially 'input-output'). A diagram of the parts and the processes is below:
This Youtube tutorial is a nice visual description of both, and how they function within a neuron.