Generally the information available indicates that there is no difference between the landing on a barge or on land in terms of the rocket itself.
The Falcon 9 1.1 Full Thrust (SpaceX continues to deny this is a 1.2 version, the theory behind that is that a change of 1.1 to 1.2 might imply a need to recertify a new version. It seems to assume people are stupid, which may be a correct assumption on this subject.) has all the modifications for landing period.
As they attempted the Grasshopper/F9DevR1 programs, they added and modified hardware to get better and better at landing. Then they tested it on a several flights, where the ASDS was not there, due to weather or other reasons.
They attempted two landings, and ran into two different hardware issues (Lack of hydraulic fluid for the grid fins first attempt, slow reacting valve second attempt) that were resolved in later builds.
This was just the next test in a long line of tests, and it succeeded.
Landing on the ASDS has complexities beyond that of LZ-1. The ASDS is a bit smaller, but if you look at the targeting in the second ASDS attempt, they got to the barge no problem. If you look at the video of the OG2 landing attempt, they hit the X marks the spot pretty much spot on. (I really want to know HOW close, and divide that by 160K to get a percentage of accuracy!)
There is a concern with the ASDS moving while a landing is under attempt. It has been noted that the ASDS is big enough, that a wave would have to be very wide in order to significantly make the ASDS tilt. Generally the arm chair critics do not consider this aspect to be a real issue.