The left one was one of the ones where the images slowly fade away and get replaced with new ones when you click them. By the time it finished, the one on the right timed out and I had to refresh the page to get a new set. When I finally managed to complete them, the login gave me an error. It wanted me to do another captcha to click OK on the error.
Steam has a bug that causes me and other people to run into continually having to do captchas. I gave up after 30.