I believe a yucatan knot is traditionally tied with the thinner double wrapping round the thicker leader. But when it is pulled up tight, the leader will end up wrapping around the double similar to the first picture.
Badfish, I actually think that the top one is not an albright at all and neither is it a yucatan in its purest form. The bottom one is definitely not a yucatan. Traditionally, an albright will have the thinner line (i.e. the braid double) doing the wrapping. As you can see, both have the thicker line do the wrapping (I am assuming the double in the bottom pic is braid). The knot in the top pic also has only one of the leader ends going through the loop which is not a characteristic of an albright.
In answering Domdomingo's question, this is what a yucatan looks like:
just looking at those pics again, do YOU use a loop in your braid and wrap your leader around it, or do YOU wrap your braid around your leader?