A primary difference is in where you plant it. An orchard takes planning. You need to make sure that the soil can sustain a whole orchard. Therefore there may be more initial tilling work to consider with an orchard. There will definitely be much more cross-pollination in an orchard than just with a single tree. Also, there will be fall out in the orchard but it won’t affect the sustainablity of the others if one should die.
There certainly will be a lot more pruning work with the orchard and nurturing for all. You won’t have the time to be so particular about the pruning as there are others waiting to be pruned. You can use the same fertilizer for them all, the same conditions will affect them all and you continue to fall back on that prudent planning for location and the readiness of the soil that you checked into at the start.
The yield of the orchard will be greater and with more variety. Therefore the fruit will be healthier for the consumer. Studies have shown that fruit grown with other fruit in variety has better vitamin content than only a single crop or one species.
Ultimately it all starts with seeds, it just takes one to plant a tree but many seeds to plant an orchard. Do you have enough seeds? Are you taking the time to prepare the soil? Are you ready and desirous to see an orchard growing or are you satisfied with just a tree?