Mac OS X Yosemite Facebook photo posts to OSX Album only
Photos on Facebook are classified as a album. Every album contains a bunch of pictures. You cannot post images separately to your timeline without having it part of a album.

When you try to post on facebook.com as a timeline photo, the images are put into a album called "Timeline Images".

When you post pictures from OS X from the share tab it puts the images in the OS X Photos album. You can manually select another album to post to from the toggle beside the text Timeline.