One important note about the difference between growing dragon fruit cactus from seed and growing dragon fruit cactus from vine cuttings (stem cuttings) is the difference in the amount of root growth at the time you either do a direct planting of the dragon fruit seedling or stem cutting, or put the seedling or cured cutting into a pot.
The dragon fruit seedlings should have a very vigorous root system established by the time you are repotting them, and if you are direct planting dragon fruit seedlings then they should really have a superior root system established and some size already. On the other hand, when you pot a dragon fruit stem cutting after it has cured (grown roots) or directly plant it, the root system will not have all the fine structure of the seedlings root system. You may well see a lag between the amount of growth you see above ground in the transplanted stem cuttings vs. the transplanted seedlings on account of this fact.
Both transplants will likely take time to get established after transplanting, but with the fine root structure already in place, the smaller seedlings may in fact show a return to growth in the visible portions of the dragon fruit cactus before the larger and more mature stem cutting does!