The banishing pentagram was created for the purpose of representing when something finishes. The invoking pentagram does the opposite. It was created for the purpose of representing something that starts. The main difference with these two stars is in the way that you make them. One is drawn starting at the bottom and the other one is drawn by starting at the top.
The banishing pentagram is created by starting at the bottom and drawing the first line straight up. The invoking pentagram is created by starting at the top and doing the opposite. You draw the line straight down. The star that seems to be the more comfortable and normal way of drawing a star is by drawing the banishing pentagram.