A spiritual advisor (or spiritual director...same thing) is a person whether a priest/religious/lay who has been trained to help guide someone in their spiritual journey. They offer the advisee advice and answer questions they may have while they travel through life's ups and downs. They can help one in their discernment, give them ideas to help them pray, let them know when they may need to look out for certain temptations, find common threads in sins they may be comitting, and well...yeah. To make it s hort, they give you spiritual advice.
A confessor is any priest who hears a confession. It is advised that most people find one priest that they will try to go to confession with regularly so that the priest can help them more (usually a person will make appointments with their confessors so that the priest doesn't feel rushed due to a line). Your confessor *could* be your spiritual director too, but that's not always the case