Sometimes these two elements are called one another. In actuality they are two different elements that have two different purposes.
Escort Cards are placed at the point of entry and have the guests name and table number or name on it. These cards tell your guests what table they are seated at. A seating chart can take the place of an escort card display.
Place Cards are used if you are assigning your guests to particular seats. There are many ways to display these cards from a simple tented card to a more elaborate set up.
Above posts will display some unique and beautiful displays of both.