Q.Lemon Tree – Tree Vs. Vine
I have been planting lemon trees from seed for a couple months, but I am noticing that some of the seeds are developing into a vine-like sapling as opposed to a more standard young tree. Is there any reason for this? Are these different types of lemons?

Certified GKH Gardening Expert
It appears that some other seed has made its way into the soil at some point. That does not appear to be a citrus.
However, if you crush the leaves and get that standard "citrus" smell... There is a chance that it could be infected with a viral infection.
This is not likely, as it would have spread to the other plants, but is a possibility.
In the meantime, this collection of articles will give you all of the information that you could need about lemons trees: